In the “Moral Animal” the author presents a study about what undesirable actions by one’s partner to men and women react more, infidelity or falling in love with someone else. The study showed that, when asked to imagine their partner sleeping with someone else, men exhibited a much more extreme mental/emotional/physiological response than when imagining their partner falling in love with someone else. For women, it was quite the opposite, imagining their partner cheating on them “romantically” was more infuriating than the prospect of them cheating on them sexually.
The evolutionary rationale behind this is as follows. For a man, if their partner cheats on them sexually, it increases the likelihood that he is going to invest his paternal resources propagating someone else’s genetic material. All of the men who have done this throughout human history are no longer in the gene pool, and thus genes which enable behaviors that avoid this situation have spread throughout the male species throughout its evolution. For a woman, emotional cheating indicates that a man will likely share more of his resources with the other woman’s offspring than with hers, decreasing the chance that her offspring will be evolutionarily fit.
One of the most pertinent questions that society today has to answer is whether knowledge of the efficacy of birth control can change our evolutionary predilections. To a man in the evolutionary environment, gaining sexual access to a woman too quickly tended to decrease the chances of commitment and male paternal investment because ease of her participating in sexual activity with a new mate indicated higher chances of infidelity. Does that still hold true if people know that any amount of sexual activity will most likely not lead to offspring, and thus males are largely safe from being caught raising somebody else’s offspring? Maybe it is the introduction of sex into modern relationships so rapidly that is causing me to shy away from marriage and avoid commitment to current sexual partners.
Regnerus potentially validates this point on page 65, though he does not go into the evolutionary logic behind it. “Men are more apt to morally disrespect such women as possible long-term partners and spouses due to their concern about future fidelity in the exchange relationship. At the same time, they value them as possible short term partners.”