This study Oxytocin Modulates Social Distance between Males and Females examines the effects of Oxytocin (OXT) on men in monogamous relationships. It demonstrates that OXT assists in maintaining fidelity to that relationship. OXT levels are increased by close and sexual interactions with their partner.
The specificity of the OXT effect in influencing the social distance that males keep from unfamiliar females is evidenced by our finding that it has no significant effect on the distance kept from unfamiliar males. Given the absence of PS differences between single and pair-bonded men in the PLC group, it is clear that for these potential fidelity-enhancing effects of OXT to be revealed, female partners would need to evoke its endogenous release immediately before contexts in which the men might encounter other women. While, compared with singles, basal concentrations of OXT in blood are increased in couples during the early stages of romantic love and stay significantly elevated in couples remaining together 6 months later (Schneiderman et al., 2012), our results suggest that further augmentation of endogenous OXT release is necessary to produce fidelity-enhancing effects. Mechanistically, this may be related to additional OXT either compensating a relative deficit (optimization hypothesis) or by collapsing already optimal levels (decompensation hypothesis). While the most obvious physiological stimulus for promoting endogenous OXT release in men would be having sex with their mate (Kru¨ger et al., 2003), the simple close presence and touch of their partner at any given moment in time might also suffice (Holt-Lunstad et al., 2008). Thus, OXT effects in promoting monogamy in males may normally depend upon the presence of a close positive relationship in the bond with their female partners and close physical proximity between the couple.1
There have been studies on the factors involved in sexual infidelity.
Virtually all American couples, married or cohabiting, expect sexual exclusivity of one another. This article asks why some people are sexually exclusive while others have sex with someone besides their mate. Previous research has linked personal values, sexual opportunities, and quality of the marital relationship to extramartial sex. This paper integrates these findings in a multivariate model that incorporates factors informing sexual decision making as well as demographic “risk factors.” Nationally representative survey data show higher likelihood of sexual infidelity among those with stronger sexual interests, more permissive sexual values, lower subjective satisfaction with their union, weaker network ties to partner, and greater sexual opportunities. With these factors controlled, gender differences are substantially reduced or eliminated, although racial effects persist. 2
Given that there are people who can maintain close relationships, simultaneously, with more than one partner.
Have there been studies examining the brain biochemistry that increases an individual's propensity for sexual infidelity?
1 Oxytocin Modulates Social Distance between Males and Females Dirk Scheele1, Nadine Striepens1, Onur Güntürkün, Sandra Deutschländer, Wolfgang Maier1, Keith M. Kendrick, and René Hurlemann The Journal of Neuroscience, 14 November 2012, 32(46): 16074-16079; doi: 10.1523/JNEUROSCI.2755-12.2012
2 Sexual Infidelity Among Married and Cohabiting Americans Judith Treas1, Deirdre Giesen2 Article first published online: 2 MAR 2004 DOI: 10.1111/j.1741-3737.2000.00048.