This isn't actually because of sexism or anything, this is the very male nature found in many species. In the wild many male animals are "not picky" and will more or less fuck anything that moves, including other males, while the females of that same species are less likely to have same sex sexual interactions or not at all. Some say it's because of the "competition to breed" and that these males need to fuck everything in order to get a good chance of reproducing, but honestly I think it's just dumb horny brain.