Verified by 
Does engaging in intercourse make you feel closer to your partner? You're not alone. There are scientific reasons why sex (especially good sex) makes you feel closer to your lover.
The neuropeptide oxytocin reduces stress and increases feelings of trust (Denes, 2012). It is also associated with feelings of love, sexual desire, and bonding among romantic couples (Birnbaum, 2017; Meston and Frohlich, 2000; Schneiderman et al., 2012). For example, couples staying together over a six-month period had higher baseline levels of oxytocin than those who had broken up within that same period (Schneiderman et al., 2012). Sexual activity and orgasm further elevate oxytocin levels for both men and women (Meston and Frohlich, 2000), increasing intimacy between partners. But oxytocin not only makes you feel closer to your mate, it also prevents you from becoming close to other potential mates, helping to maintain fidelity. Men in monogamous relationships who were administered oxytocin intranasally maintained a greater distance between themselves and an attractive female confederate. These men stayed farther away from the attractive woman versus men in the placebo condition and versus single men (Scheele et al, 2012). Oxytocin helps to make you feel closer to your partner and keep you closer too.
Pillow Talk
Many lovers engage in "pillow talk" after sex. More self-disclosure after sex is associated with increased closeness and relationship satisfaction (Denes, 2012). Interestingly, women who achieved orgasm during sex engaged in more pillow talk than men and more than women who did not achieve orgasm. (Learn other relationship benefits to the female orgasm here.) These women also tended to say more positive things about their relationships in their post-sex disclosures to their lovers. The physical act of sex may not even be necessary to increase self-disclosure, merely being subliminally exposed to to sexual stimuli encouraged more intimate self-discluosure among strangers of the opposite sex (Birnbaum et al., 2017). Sharing secrets has been shown to increase intimacy (Aron et al., 1997), which, in circular fashion, may then in turn increase sexual desire (Birnbaum et al., 2017).
Afterglow
Meltzer and colleagues (2017) define sexual afterglow as "enhanced sexual satisfaction that lingers following sexual activity." (Learn more about your sexual afterglow here.) In essence, some couples stay sexually satisfied long after intercourse has ended. In some couples, their sexual satisfaction lasts for up to two full days. Furthermore, the longer their sexual afterglow lasted, the more marital satisfaction couples reported over time. These researchers suggest that this afterglow functions to promote bonding in romantic couples. They also speculate that a longer afterglow might reduce a couple's risk for infidelity.
Similar Brain Activity
As mentioned above, the neurotransmitter oxytocin is associated with feelings of love and sexual desire. Additionally, similar areas of the brain are active when we experience love and sexual desire. The thalamus, hippocampus, and anterior cingulate cortex are activated when individuals feel both love and sexual desire (Cacioppo et al., 2012). Other research suggests additional similarities. Stoessel and colleagues (2011) found that the anterior cingulate cortex, the insula, and the posterior cingulate cortex were active when individuals viewed photographs of their loved ones, as well as erotic photographs of strangers. The common neural pathways to sexual desire and love lead researchers to suggest that love grows out of the pleasant feelings of sexual desire and fulfillment (Cacioppo et al., 2012).
Whether your relationship is brand new or decades old, good sex can make your relationship closer.
Portions of this post were adapted from The Social Psychology of Attraction and Romantic Relationships. Copyright Madeleine A. Fugere, 2015.
References
Aron, A., Melinat, E., Aron, E. N., Vallone, R. D., & Bator, R. J. (1997). The experimental generation of interpersonal closeness: A procedure and some preliminary findings. Personality and Social Psychology Bulletin, 23(4), 363-377.
Birnbaum, G. E. (2017). The fragile spell of desire: A functional perspective on changes in sexual desire across relationship development. Personality and Social Psychology Review, 1088868317715350.
Birnbaum, G. E., Mizrahi, M., Kaplan, A., Kadosh, D., Kariv, D., Tabib, D., ... & Burban, D. (2017). Sex unleashes your tongue: Sexual priming motivates self-disclosure to a new acquaintance and interest in future interactions. Personality and Social Psychology Bulletin, 43(5), 706-715.
Cacioppo, S., Bianchi‐Demicheli, F., Frum, C., Pfaus, J. G., & Lewis, J. W. (2012). The common neural bases between sexual desire and love: a multilevel kernel density fMRI analysis. The journal of sexual medicine, 9(4), 1048-1054.
Denes, A. (2012). Pillow talk: Exploring disclosures after sexual activity. Western Journal of Communication, 76(2), 91-108.
Meltzer, A. L., Makhanova, A., Hicks, L. L., French, J. E., McNulty, J. K., & Bradbury, T. N. (2017). Quantifying the sexual afterglow: The lingering benefits of sex and their implications for pair-bonded relationships. Psychological science, 28(5), 587-598.
Meston, C. M., & Frohlich, P. F. (2000). The neurobiology of sexual function. Archives of General Psychiatry, 57(11), 1012-1030.
Scheele, D., Striepens, N., Güntürkün, O., Deutschländer, S., Maier, W., Kendrick, K. M., & Hurlemann, R. (2012). Oxytocin modulates social distance between males and females. Journal of Neuroscience, 32(46), 16074-16079.
Schneiderman, I., Zagoory-Sharon, O., Leckman, J. F., & Feldman, R. (2012). Oxytocin during the initial stages of romantic attachment: relations to couples’ interactive reciprocity. Psychoneuroendocrinology, 37(8), 1277-1285.
Stoessel, C., Stiller, J., Bleich, S., Boensch, D., Doerfler, A., Garcia, M., ... & Forster, C. (2011). Differences and similarities on neuronal activities of people being happily and unhappily in love: A functional magnetic resonance imaging study. Neuropsychobiology, 64(1), 52-60.
