|A humans as "reactive chemicals" view of love the chemical reaction along with some type of "chemical equation of love" of the form:|
or you plus me to the power of infinity equals love.
The conception of love as a chemical reaction is view of life that people, over the the last two-hundred years, beginning generally with the publication of the 1809 novella Elective Affinities, have speculated on, mused over, and debated to no end. 
In modern terms, the debate continues, with those on the philosophical side considering love to be something beyond the ken of scientific analysis and those on the practical or factual side considering love to be a chemical process; the latter view of which particularly owes its standing to the publication of the results of recent neurochemical studies: the 1959 pheromone theory of mate attraction, the year bombykol was synthesized (by German chemist Adolf Butenandt), a chemical released by the female silkworm to attract mates; the 1976 endorphin theory of love (endogenous heroin); the 1980 chocolate theory of love (PEA theory); the 1990s oxytocin theory of love (the "cuddle chemical" explanation for the attachment of pair bonding), among others, such as the "limbic system" theory of love.
According to a 2005 poll, 65.5% of people consider love to be a chemical reaction. 
The first magazine to boast a cover defining love as a chemical reaction was the Valentine's Day special February 2006 issue of National Geographic, shown adjacent, which outlined the latest research on the brain chemistry involved in the various transition stages of romantic love. 
| Left: A 2005 poll results of 100 Americans on the query: "is love a chemical reaction?", finding that 65.5% of Americans believe that love is a chemical reaction.  Right: an AllPosters.com Valentine's day poster/picture depicting love as a chemical reaction. |
Johann von Goethe who, after studying chemistry for a period of fifty years, along with having attended the weekly lectures of his life-long friend German chemist Johann Dobereiner, conceived a view that human relationships are elective affinity reactions that can be quantified by affinity tables. 
In April 1808, Goethe dictated a large part of his new theory that the vicissitudes of love in relationships and marriage are elective affinity reactions to his friend Heinrich Meyer. In October 1809, Goethe published his "chemical treatise on the origin of love" as a coded novella entitled Elective Affinities in which the characters, specifically in chapter four, book one, debate whether or not they are chemical species and in particular whether or not they have "choice" in their their friendships, relationships, and love affairs.
One of the first to explicitly state that love is a chemical process was Swiss psychiatrist Carl Jung. In his 1933 book Modern Man in Search of a Soul, Jung stated: 
In film, the first to state that love is a chemical process was Swedish-born American actress Greta Garbo. Specifically, in the 1939 film Ninotchka, Garbo informs Melvyn Douglas that: 
“Love is a romantic designation for a most ordinary biological—or, shall we say, chemical—process … a lot of nonsense is talked and written about it.”
| Left: A 2007 video series on the query "Is Love a Purely Chemical Reaction?" [Intro, Part 1 (above), Part 2, and Part 3] by American electrochemical engineer Libb Thims.|
Right: Cover story: "Love: the Chemical Reaction", in the February 2006 (Valentine's day) issue of National Geographic.
In 1979, American psychologist Dorothy Tennov, in her Love and Limerence, outlined a Freudian-like theory of a state of love, characterized by ambivalent but not complete rejection combined with intrusive thinking, called "limerence", modeled on French writer Stendhal 1822 theory of crystallization from his book On Love, and outlined a number of steps or mechanisms involved in a "limerent reaction" between the rejected person and the object of desire of the limerent person. The limerent reaction is a composite reaction; that is, it actually describes a unique series of reactions. These reactions occur only where misperceptions meet adversity in the context of a romance. Perhaps because of this unique specificity, limerent reactions can be uniquely quantified and predicted according to the schema of six steps. Tennov estimates, based on both questionnaire and interview data, that the average limerent reaction duration, from the moment of initiation until a feeling of neutrality is reached, is approximately three years. 
In 1993, American psychologist Harville Hendrix stated in his book Keeping the Love You Find: a Guide for Singles, in what has become notable quote, that: 
“When we meet an Imago match, that chemical reaction occurs and love ignites. All other bets, all other ideas about what we want in a mate are off. We feel alive and whole, confident that we have met the person who will make everything all right.”
|A section on the back cover of the 2007 textbook Human Chemistry, by American electrochemical engineer Libb Thims, showing cupid, two people in love, and the famous 1939 Ninotchka film quote by Greta Garbo.|
This has been translated, by some, to the conclusion that “physiologically, romantic love is a chemical reaction”.  In the 1999 article “The Science of Love”, writer Nuna Alberts explains that “researchers believe that love at first sight is not just a cliché: a chemical reaction which may lead to romance can be created when one person first looks at another.” 
Love at first sight
In the late 1990s, American market research Earl Naumann interviewed 1,495 people across American, by phone, whose answers to questions on their views about “love at first sight” were tape recorded, documented, and statistically analyzed.  On this topic, according to Naumann, as we perceive our environment, and the inclusive “potentials” in that environment, through our senses of sight, smell, touch, and hearing that it is sensor information that triggers the chemical reaction of love.
The results of his studies found that nearly two-thirds of the population believes in love at first sight; that of believers, more than half have experienced it; that 55% of those who experience love at first sight married the object of their affection and that three-quarters of those who married as a result of love at first sight have stated married well over the national average. In a nutshell, this means, approximately, that 20% of people will fall in love at first sight, solely by the operation of a visual field particle stimulus (photons), marry that person, and that of those people, three-fourths will stay marry better than the national average.
Subsequently, the visual stimulus of sight, as is the case with most sensor information, will enter the brain system through the optic nerve and go to the thalamus (the brain's translator); these messages, in turn, are then simultaneously sent to the neocortex (the thinking part) and the amygdala (the place where deep memories and fear are stored). The amygdala then sends messages to the hypothalamus (the part that connects the nervous system to the endocrine system), which then directs the pituitary gland to release the appropriate hormones and neurochemicals.
|A 2009 correction video by American electrochemical engineer Libb Thims to correct Chinese chemical engineer Anthony Fong who stated from his university office at Shantou University that the love viewed as a chemical reaction is a myth.|
Chemical mechanism views
In the 2006 book The Letter of Love, author Linda Hargesheimer clearly stated that: “Love is a chemical reaction between people that causes the physical attraction." Moreover, she noted that: “a chemical reaction also exists between friends.”  This latter supposition digs into the fact that all variations of human interactions, such as friendships, family dynamics, social interctions, work relations, etc., can be diagrammed as chemical reactions. 
When modeling human chemical reactions, as is the case with any type of chemical reaction, one uses "chemical equations" to define the process of the reaction, in which the "reactants" are the chemical entities that go into the reaction and the "products" are the transformed entities that the results of the reaction. A chemical reaction, by definition, is "the coming together, or interaction, of two or more atoms, ions, or molecules with the result that a chemical change takes place and a new substance is formed, with a different chemical composition."  On this definition, over the last dozen years, a few individuals, such as American chemical engineer Libb Thims (1995), American astrophysicist Christopher Hirata (2000), American computational chemist David Hwang (2001), with his article "The Thermodynamics of Love", and Canadian writer Chanel Wood (2007), have independently arrived at the view of the process of falling in love as a chemical reaction in which reactant transform into products:
Reactant + Reactant → Product
In technical terms, the basic couple forming reaction, in which a man Mx meets a woman Fy, and they chemically bond to form the product of a couple MxFy, is written as:
Mx + Fy → Mx≡Fy
|Left: a 2001 online Q&A posting, Americans geneticist and veterinarian Tamara McArdle and a seven-year-old student named Jason, hosted by the Physics Van Outreach program of the physics-engineering department of the University of Illinois at Urbana-Champaign, a quote that drove the construction of the 2007 textbook Human Chemistry. Right: an anthropomorphized cartoon-style "humans as chemicals" view of love being viewed as a purely chemical reaction and reproduction (a baby test tube).|
in which the chemical entities "Mx" and "Fy" are human molecules and in which the bonded entity "Mx≡Fy" is what is called a dihumanide molecule; the prefix di- meaning two, the suffix -ide meaning like or similar to or, more specifically, referring to a chemical compound derived from or related to another, usually specified, compound. This is analogous to a dioxide molecule O2 in which two oxygen atoms are bonded in one cohesive unit.  Hence, by definition, in the big picture point of view, the process of love is a purely chemical reaction.
In the 2001 book The Truth about Love, Canadan author Elizabeth Currie not only stated that love is a chemical reaction, but also discusses some of the key unconscious triggers to interpersonal chemical reactions of pair bonding.  In particular, Currie states that romantic love is the anticipation of getting a “key”, such that one will feel the state and euphoria of romantic love if they collide with someone who can provide that key. She states, by example, “if you have money as a key, you will have a ‘chemical reaction’ to potential mates with money. If you have acceptance as a key, you will have a ‘chemical reaction’ with good social standing. If you have marriage as a key, you will have a ‘chemical reaction’ to anyone who is looking to for a marriage partner.” In sum, she notes that her examples are oversimplified, but they demonstrate “the point that the new chemistry, or special magic, you feel for another person is for a reason; that person can provide you with a key you need.”
Objections | Religion and philosophy
Of those 35% of people who object to the view of love being a chemical reaction, a predominately large proportion of objectors tend to be basing their objection on religious or philosophical grounds; in other words, the chemical view conflicts with their belief system.
The idea that love is a chemical reaction between human molecules is, to some, considered as a joke or nonsense, and to others considered something beyond the realm of science, or rather a philosophical subject, not to be touched by hard science.
In 1810, for instance, after reading Elective Affinities, Goethe's fellow author and neighbor Christoph Wieland sent a letter (which he suggested should be burned after it is read) to his close friend German philologist and archeologist Karl Böttiger stating that: 
“To all rational readers, the use of the chemical theory is nonsense and childish fooling around.”
Wieland, to noted, objected on religious grounds; supposedly due to the radicalness of its Christianity. In similar theme, in 1922 American philosopher Frederick Bennett published an article entitled “Is Spirit a Chemical Reaction?”, in which he states that he objects to the following quote given by a scientist (arrived at as a result of researches) in a local newspaper:
“Love is in its ultimate analysis nothing but a chemical reaction.”
Bennett goes on to argue, similar to Wieland, that this statement is false and puerile (or childish), on the grounds that the human soul is not a chemical compound nor of material composition and thus not worthy of explanation by science. 
|A 2011 reaction video by an religious-themed American YouTuber who sees the notion of love being viewed as a chemical reaction to be “horsehockey” (bull-crap in plain speak), being that it conflicts with (a) the Bible and (b) his philosophical outlook, which he lists as "Holy Bible (KJV), Atlas Shrugged by Ayn Rand, The Creature from Jekyll Island by Edward Griffin, Les Miserables by Victor Hugo, and Mere Christianity by C.S. Lewis."|
In 2005, to cite one of many examples, after reading the “chemical reaction” section to the Institute of Human Thermodynamics’ Top 150 Definitions of Love webpage, an American high school geology teacher commented, to American chemical engineer Libb Thims, that the concept of “human chemical reactions” occurring between “human molecules” was: “good for a laugh, but not much else.” 
The man in the adjacent "reaction video" (reaction to another YouTuber video which had the statement love is a chemical reaction) comments the following heated reaction view:
“Let’s focus on that one statement: ‘love is a chemical reaction’. That’s an incredibly deep statement and I think it’s a lie from the pit of hell.”
The man objects because the chemical view conflicts with the Bible.
The following are related quotes:
“Loneliness, like any other emotion, is just a chemical reaction in your brain, as is possible with all emotions, you can control it … Unfortunately, we oftentimes lack the power to do so.”— Aedan Clarke (2013), Tumblr post (Ѻ); reblogged 198+ times
“Listen, Morty, I hate to break it to you but what people call ‘love’ is just a chemical reaction that compels animals to breed. It hits hard, Morty, then it slowly fades, leaving you stranded in a failing marriage. I did it. Your parents are gonna do it. Break the cycle, Morty. Rise above. Focus on science.”
The following are related love as a chemical reaction images:
|Image from a Oct 2015 Reddit thread (Ѻ) discussing the 27 Jan 2014 love philosophy of Rick of the Rich and Morty show.|
● Human chemistry
● Science-based online dating sites
|Left: Rick (Ѻ), from the Rick and Morty show (2014), schooling Morty on love. Right: a test tube view of love as a chemical reaction, alluding to the notion that love is a "human chemical reaction" (a surface-attached chemical reaction) between people viewed as "human chemicals" (or human molecules), and is a process (falling in love) involving heat (or fire), electricity (sparks), love (and hate), among other factors, such as music, money, happiness, a cold body, cocktails (lowers activation energy barrier), etc., out of which, in the case of a human reproduction reaction, a child (new human molecule) (precipitate) is synthesized.|
1. (a) Is Love a Purely Chemical Reaction? (question asked in 2001 by Jason, age 7, from Glenside Weldon, Pa) - "Ask the Van", part of the Physics Van outreach program at the Department of Physics at the University of Illinois.
(b) Question answered by Tamara McArdle a veterinarian practicing in the Champaign-Urbana area who has done research in genetic modeling and cancer prevention.
(c) Thims, Libb. (2007). Human Chemistry (Volume One) (pg. xxi). Morrisville, NC: LuLu.
2. (a) See: Goethe's human chemistry
(b) Tantillor, Astrida O. (2001). Goethe's Elective Affinities and the Critics. New York: Camden House.
(c) Adler, Jeremy. (1987). “Eine fast magische Anziehungskraft”. Goethe’s “Wahlverwandtschafte” und die Chemie seiner Zeit (“An almost Magical Attraction”). Goethe’s Elective Affinity and the Chemistry of its Time), Munich.
(d) Adler, Jeremy. (1990). "Goethe's use of chemical theory in his Elective Affinities" (ch. 18, pgs. 263-79) in Romanticism and the Sciences - edited by Andrew Cunningham and Nicholas Jardine, New York: Cambridge University Press.
(e) Thims, Libb. (2007). Human Chemistry (Volume Two), (ch. 10: "Goethe's Affinities", pgs. 371-422), (preview), (Google books). Morrisville, NC: LuLu.
3. Thims, Libb. (2005). "Poll: Is Love a Chemical Reaction?", Research Project #4, Chicago: Institute of Human Thermodynamics.
4. Slater, Lauren. (2006). "True Love", National Geographic, Vol. 209, No. 2, pgs. 32-49, February.
5. (a) Jung, Carl. (1933). Modern Man in Search of a Soul, (pg. 49). Routledge.
(b) Carl Jung: "The meeting of two personalities is like the contact of two chemical substances" - QuotationsBook.com
6. Ninotchka (1939 film) – Wikipedia.
7. Quote Garbo (Article): “The Right Chemistry”, Time Magazine, Feb. 15, 1993.
8. (a) Human Chemistry (PDF cover file) - LuLu.com
(b) Thims, Libb. (2007). Human Chemistry (Volume One), (preview), (Google books). Morrisville, NC: LuLu.
(c) Thims, Libb. (2007). Human Chemistry (Volume Two), (preview), (Google books). Morrisville, NC: LuLu.
9. (a) Hendrix, Harville. (1993). Keeping the Love You Find: a Guide for Singles, (pg. 21). Pocket Books.
(b) Atwood, Nina. (1996). Be Your Own Dating Service: a Step-by-Step Guide to Finding and Maintaining Health Relationship, (pg. 33). Macmillan.
10. Luquet, Wade. (1996). Short-term Couples Therapy: The Imago Model in Action, (pg. 3). Psychology Press.
11. (a) Naumann, Earl. (2001). Love at First Sight – the Stories and Science Behind Instant Attraction, (ch. 2: “The Chemistry of Love”, pgs. 23-42 ). Naperville, IL: Casablanca Press.
(b) Earl Naumann – the Science behind Instant Attraction.
12. Hargesheimer, Linda H. (2005). The Letter of Love: A Guide to Unconditional Love, the Soul’s Purpose and Human Energy Connection, (pg. 29). Publisher: Hargesheimer.
13. Clark, John O.E. (2004). The Essential Dictionary of Science. New York: Barnes & Noble Books.
14. Currie, Elizabeth. (2001). The Truth about Love, (pg. 48). Trafford Publishing.
15. Wieland, Christoph Martin. (1810). "Letter to Karl August Böttiger" July 16. Weimar. Quoted from Tantillo 2001, pg. 9-10.
16. (a) Thims, Libb. (2007). Human Chemistry (Volume Two), (pg. 673). Morrisville, NC: LuLu.
(b) Thims, Libb. (2004). “Poll: What is Love?” (section: Chemical Reaction”). Chicago: IoHT Publishing.
17. Tennov, Dorothy. (1999). Love and Limerence: the Experience of Being in Love. New York: Scarborough House.
18. Alberts, Nuna. (1999). “The Science of Love (the Chemistry of Romance)”, Life, 22, 38(1), Feb. ISSN: 0024-3019.
19. Bennett, Frederick M. (1922). “Is Spirit a Chemical Reaction?”, The Personalist (pgs. 106-11), Vol. 3-4. School of Philosophy, University of Southern California.
20. Valentine Cartoon, Chemical Reaction – AllPosters.com.
● Winerman, Lea. (2009). “Love is a Chemical Reaction: Scientists Find.”, Online NewsHour, Feb 14, PBS.org.
● How to Understand Love as a Chemical Reaction – WikiHow.com
● Is Love Nothing but a Chemical Reaction? - WikiAnswers.
● Love: Nothing More Than A Chemical Reaction (65% for, 35% against) 23 Nov 2008 – ForAndAgainst.com