>>57044229>I don't know whythe actual psychology answer is that transgressing boundaries for the sake of an intimate partner demonstrates affection for and devotion to that partner
everything in our behavior is sexually selected for
if a girl has a lot of affection for you, then you're more likely to have sex with her and pass on your genes
if she has a crazy amount of affection for you, as demonstrated by her breaking some taboo for you, then you're even more likely to have more kids and pass on more genes
if she's exclusively devoted to you, in that she does stuff for you that she would never do for anyone else, then there's a much better chance that the kids that she has (and which you will almost certainly put tons of time, effort, resources, and opportunity cost into helping raise, since humans are a k-selected species) will actually be yours and have your genes, instead of someone else's
and to the extent that a girl perceives that the guy views buttsex as a taboo that he wouldn't generally want to engage in, but he's doing it with her, then it reinforces all of the above from the other side of the relationship as well
of course, none of that evolutionary stuff is in guys' minds when they're thinking about how much they want to plow a girl's ass
guys who want this aren't thinking
>you know, I would really like my dick to be inside of an anus, potentially sliding against poopthey're thinking
>I want to find a woman who loves me so much that she would want to do pretty much anything for me >I want to mean so much to someone that she wouldn't even be able to stop herself, she would just be enthralled by how much she loves meof course, you can still have a great (and evolutionarily-successful) relationship without breaking taboos like this
or one where you break different taboos for your partner other than buttsex
