This article has a very good discussion of the factors in short and long-term love:
Love in the Brain
Clare Smiga
Does brain equal behavior? Some people have argued that they have difficulty saying it does because they find it hard to believe that our individual, tangible brain controls emotions that many consider to be intangible, such as being in love. This paper will discuss the role that the brain actually plays in love- why we are attracted to certain people, why we feel the way we do when we are around them, and whether or not this is enough to say that in the case of love, brain does equal behavior.
The first stage of romantic love begins with attraction. Whether you have been best friends for a long time or you just met the person, you begin your romantic relationship when there is that feeling of attraction. But why are we attracted to some people and not to others? Some research and experimentation suggests that pheromones play a role in attraction ((1), (2), (3), (4)). Although the existence of pheromones in humans and the method by which individuals detect them is still under debate and requires further research, a study by Stern and McClintock on pheromones in women's underarm secretion gives the most solid evidence for the existence of human pheromones ((5)). It has been hypothesized that the brain detects these pheromones through an organ known as the vomeronasal organ (VNO), by receptors, or by the terminal nerve in the nostrils ((5)). Despite the fact that pheromones and how they are detected in humans is controversial, it has been suggested that selectivity for certain pheromones might explain why we are only attracted to certain people ((6)).
Research agrees, however, that whether or not pheromones exist, they are not the only reason we are attracted to an individual. Other factors such as social and environmental influences, genetic information, and past experience contribute to who we are and who we find attractive physically and emotionally ((5), (7)). In addition, an experiment by McClintock showed that women were attracted to the smell of a man who was genetically similar, but not too similar, to their fathers ((1)). Therefore, our genetic information might play a role in whether or not someone is desirable in order to avoid inbreeding or, on the other end of the spectrum, to avoid the loss of desirable gene combinations. Inevitably, however, it is our brain that processes another individual's appearance, lifestyle, how they relate to past individuals we have met, and, possibly, their pheromones. Then, based on this information, we decide, within our brain, whether or not this person is worth getting to know.
Almost immediately thereafter, it is uncontroversial that when someone experiences an attraction for someone else, their brain triggers the release of certain chemicals. These adrenaline-like chemicals include phenylethylamine (PEA) which speeds up the flow of information between nerve cells, dopamine, and norepinephrine (both of which are similar to amphetamines). Dopamine makes you feel good and norepinephrine stimulates the production of adrenaline. Together, these chemicals explain why when we are around someone we are attracted to we feel a "rush" and our heart beats faster ((8)). However, if you have ever been in love, you know that these feelings somewhat subside as you become more comfortable with someone and move from that attraction and "lust" stage to love.
But what is the role of the brain in the stage of love? One chemical, oxytocin, plays an important role in romantic love as a sexual arousal hormone and makes women and men calmer and more sensitive to the feelings of others. Physical and emotional cues, processed through the brain, trigger the release of oxytocin. For example, a partner's voice, look or even a sexual thought can trigger its release. Attachment to someone has been linked to chemicals released from the brain known as endorphins that produce feelings of tranquility, reduced anxiety, and comfort. These chemicals are not as exciting as those released during the attraction stage, but they are more addictive and are part of what makes us want to keep being around that person we are in love with. In fact, the absence of these chemicals when we lose a loved one plays a part in why we feel so sad ((8), (9)). But is that it? Are chemical releases triggered by the brain when we think of or are in the presence of our partner all there really is behind those "I love you's"?
Other research has shown that there are certain areas of the brain linked with being in love with someone. It is possible that our feelings for our partner are somehow stored in our brain. Researchers have found that when individuals are shown pictures of their loved ones, areas of the brain with a high concentration of receptors for dopamine are activated. Moreover, MRI images of the brains of these individuals showed that the brain pattern for romantic love overlapped patterns for sexual arousal, feelings of happiness, and cocaine-induced euphoria. This overlap and, at the same time, unique pattern indicates the complexity of the emotions that comprise romantic love ((6), (10)). These results did not occur when the individuals were shown pictures of non-romantic loved ones. Another similar experiment showed that individuals produced activity in the medial insula and the anterior cingulate of the brain. The former is a part of the brain associated with "gut feelings" and the latter is associated with feelings of euphoria ((11)).
Other areas of the brain that have been associated with love include the septal area, which has been associated with pleasure, and the frontal lobe, the most highly evolved part of our brain, which has been associated with higher mental functions such as trust, respect, desire for companionship, etc ((12)). Finally, the amygdala, which has direct and extensive connections with all the sensory systems of the brain and with the hypothalamus, is considered to be the emotional center of the brain. Therefore, it most likely also plays a role in the emotions surrounding love ((13), (14)). Consequently, it is highly likely that as we become more attached to someone through experience and time together, our love for them is processed and stored in our brain.
So if everyone in love is experiencing the same chemicals and activating the same areas of the brain, what makes love such a special experience? What makes your feelings any different from anyone else's? It is that person that you have fallen in love with. It is them and only them that can do or say the right things and touch you the right way so that those chemicals are released and those areas of the brain are activated. Finally, is love just a function of our brains? As shown by the experiment with college students, the pattern within the brain that formed when they saw their loved ones was complex, as are our brains. Although it is your partner's brain that enables them to act or say those things that trigger your brain to respond with those chemicals of attraction and attachment, everyone's brain is individual and makes up an individual "you" and that unique and special experience that we call love. Although this does not rule out other areas that many believe play a role in love, such as the soul, it shows that the brain does play a vital, if not ultimate role in all aspects of love and that this role is extremely complex and unique.
