Hmmm....men are fairly highly pressured by (modern western) society to not get attached after sex, and are somewhat likely to deny or at least play down feeling

Hmmm....men are fairly highly pressured by (modern western) society to not get attached after sex, and are somewhat likely to deny or at least play down feelings of attachment that they might naturally feel - even to themselves. I'm not sure how you'd be able to control for that sort of bias in any kind of rigorous study, or how much variation might be left if you did.