Love for One? The Special Case of Romantic Love

"Layla and Manjun" tile panel, 17th century.

Source: Public domain; The Museum of Fine Arts, Houston

If you’ve ever been in love, you know the euphoria of being with and thinking about your beloved. You yearn to know all about them, hear about their day, and life seems more meaningful. You hear a song and think about them, long to hear their voice, and text throughout the day.

This is romantic love, Western-style, which scientists define as “an intense desire for union with a specific other.” Interestingly, according to many Eastern and spiritual traditions, love is a desire for the well-being of “all” and not just one person (i.e., Dalai Lama, 2006). Therefore, many of these traditions shun the idea of attachment to one individual, theoretically freeing many of us from attachment and suffering.

Perspectives that minimize the role of romantic love or the ascribing of “special meaning” and devotion to a specific individual are not wrong, per se. These views were appropriate for their times. However, they do not consider modern scientific advances that show that there are underlying biological systems that play a major role in romantic love (Acevedo et al., 2020). Indeed, ascribing “special meaning to specific others” is the basis of love and “attachment.” Attachment bonds, observed in humans and other mammals, serve many important functions including reproduction, raising of offspring, caregiving, and long-term companionship (Bowlby, 1969; Conroy-Beam, Goetz).

Western theory and scientific advances on the biology of love suggest that it is in the fabric of our genes to ascribe special meaning and value to a specific “other.” In fact, it is considered insensitive and cold for a person not to behave in a caring and nurturing way towards a child, family member, or spouse. Conversely, it may be perceived as inappropriate for an individual to display the same level of affection towards a stranger as they would towards their child, spouse, or friend.

Although there are many types of love—including friendship love and kin love—the focus on romantic love tends to occur within the context of pair-bonds. Pair-bonds are characterized by biologists as a select partner preference where the couple shares territory, engages in coordinated behaviors together such as grooming, feeding, and mating, and some raise offspring together (Walum & Young, 2018). In humans, romantic love is thought to have evolved for reproduction, the bi-parental care of offspring, and long-term companionship (Acevedo et al., 2019).

Psychological theories of romantic love propose that it is “an intense longing for union with another individual,” not just physical union but emotional, cognitive, and spiritual union as well (Hatfield & Rapson, 1996). A common theme among models of romantic love is that it is a “select” partner preference, where the “partner” takes on special meaning.

Often in committed, in-love relationships, the partner becomes integrated into the self-concept as shown by numerous studies of self-expansion using the Inclusion of Other in the Self Scale (for review, see Branand, Mashek, & Aron, 2020). Merging with the partner is a cardinal feature of romantic relationships and marriages—not only concerning emotional and cognitive aspects of the self, but also practical life matters such as social networks, finances, and in some cases even careers and life missions (Cuber & Haroff, 1965).

Taking on special meaning, then, the beloved partner becomes the focus of the lover’s attention, consuming a large part of their cognitive space which often includes idealization, where the lover places a high value on the beloved and fails to see any flaws (Murray, Holmes, & Griffin, 1996). Incidentally, idealization of the partner, also known as “positive illusions” by psychologists, are associated with a variety of relationship benefits including greater relationship satisfaction, love, and trust; as well as less conflict in both dating and marital relationships (Murray & Holmes, 1997). Correspondingly, studies of individuals in-love have shown that romantic love is positively associated with thinking about the partner, having positive thoughts about the partner, and the percent of an average day spent thinking about the partner (O’Leary, Acevedo, & Aron, 2011; Fisher, Aron, & Brown, 2006).

Brain imaging studies have confirmed self-report research suggesting that in romantic love, the partner takes on “special meaning.” For example, numerous studies have shown that in response to face images of the partner (versus controls for facial familiarity and closeness), individuals in-love show heightened activation in brain regions that mediate reward, motivation, euphoria, attention, and higher-order cognitive processes (Acevedo et al., 2011, Aron et al., 2005; Xu et al., 2011).

In a recently published study, my collaborators and I tested newlyweds around the time of marriage and a year later (Acevedo et al., 2020). They also provided saliva samples for genetic analysis of vasopressin, oxytocin, and dopamine genes implicated in pair bonding. The findings showed robust evidence of the dopamine reward system’s involvement in romantic love and its maintenance among the group of newlyweds scanned over the first year of marriage. The dopamine reward system is interesting because it is implicated in motivation, energy, working for rewards, and is associated with corresponding emotions such as excitement, euphoria, and energy, as well as frustration if the drive is thwarted. In another study, activation in dopamine-rich reward regions was associated with commitment and relationship longevity as shown in a two-year study with young adults in China (Xu et al., 2012).

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In addition to dopamine-rich activations, individuals in-love also show enhanced activity, triggered by images of the partner, in brain regions that are rich in oxytocin and vasopressin receptors as a function of their romantic love scores (Acevedo et al., 2011, 2020). Oxytocin is involved in a variety of complex social behaviors including trust, eye gaze, parental nurturing, empathy, and pair-bonding (for review, see Feldman, 2012). Some researchers have even suggested that oxytocin is the "moral molecule” because it is involved in a variety of prosocial behaviors (Zak, 2013).

Another common expectation of romantic relationships is caring, empathy, and altruism. Although altruism is somewhat more variable and lenient in pair-bonds (many couples may not consider a partner that would not be willing to die for them a "deal-breaker”), kindness is one of the top variables that both women and men desire in a partner (Buss & Barnes, 1986). However, altruism is different than monogamy in that it is applied more widely, beyond the pair-bond. Altruism is thought to be rooted in neurobiological mechanisms to promote offspring care, being observed most prominently in kin and close relationships, but also extending to others (Preston, 2013). However, evolution is thought to have conserved altruism to respond to others’ needs, even at a cost to the self, with the function of promoting survival and cooperation of the species (Batson, 2011; deWaal, 2008).

Relationship researchers have considered the existence of altruistic love as an important factor for relationships. Indeed, a large survey study conducted at the National Opinion Center in Chicago showed that greater self-reported altruism towards a partner was associated with more marital happiness and commitment (Smith, 2006). That is, 40 percent of married individuals ranked near the top of the altruism scale, while only 25 percent of divorced and separated respondents and 20 percent of those who had never married endorsed high levels of altruism. The take-home message is that beyond romance, altruism is an important factor in entering and staying in a happy marriage.

Scientists have confirmed the importance of altruism for sustaining in-love marriages with brain studies. For example, in one neurobiological study of altruism in marriages, findings showed that individuals’ altruism scores were positively correlated with their passionate love scores (Acevedo et al., 2019). Moreover, altruism towards a partner was significantly associated with an oxytocin gene variant (OXTR rs53576), which mediates complex social behaviors including empathy (Buffone and Poulin, 2014) and overall sociality (Li et al., 2015). In this study, newlyweds were shown various empathy/emotion-inducing (happy and sad) and neutral face images of the partner and a stranger.

Results showed that in response to partner’s happy and sad faces, newlyweds altruism scores were strongly associated with brain response in the ventral pallidum (VP), an area of the brain that is critical for attachment and pair-bonding (see Acevedo et al, 2019 for review). This pattern of response was not shown in response to strangers’ face images. Importantly, this suggests that the social mind discriminates, showing at a very basic level a stronger response to a partner’s versus a stranger’s emotional displays. This work suggests that beyond romance and sexual monogamy, selfless caring for a partner also plays also a pivotal role in marital love and happiness.

For many romantics, it may seem overly clinical to know that there are hormones, genes, and chemical reactions orchestrating the magic of love. But genes and brain activity are just some of the components of love and romance. Humans are creative and clever, and have a very large cortex that allows them to engage in complex thinking and behaviors which facilitate all the romantic stuff that makes love magical, and putting the needs of the relationship before their own, perhaps unknowingly, ultimately benefiting the greater good for all.