^ That's basically what I've heard.
Looking at it from a biological frame of mind, there isn't any "cost" to a woman if her man is promiscuous and impregnates other women. She's still having her own kid, no matter what, with a guy with great genes/abilities (aside from being a cheater.. which actually in a roundabout way means that he's pretty skillful)
But if a woman has sex with another man, her husband might raise that other man's children. The husband might have no children of his own. That's suicide for his genetic line.
What would be costly for a woman is if her man fell in love with another woman, meaning that he might leave her and she'd lose all the economic advantages he provided, and if they had children, no mate to help provide. This explains why woman are more troubled by "emotional cheating", it has a higher cost to women's reproductive potential. While a man is more troubled by "physical cheating", it has a higher cost to a man's reproductive potential. Of course men and women will both feel some betrayal at either form of cheating, but at a primitive emotional level, the physical cheating will bother the man more, and the emotional cheating will bother the woman more.
People are so much more complicated than that in many ways... but it explains where our deep, automatic emotions about relationships often come from.
Great post. Leading on from that the risks women take when they have sex are far greater than that for men. If a man has sex, in the purely animistic world in which we evolved, the father bears absolutely no responsibility for the potential child and pays little to no cost. The female on the other hand risks a pregnancy involving drastic bodily changes, death before or during labour and then 14-18 years of childcare. Its for this reason that the whole "slut" paradigm exists. Its deeply wired into our us.
