Men who are frustrated that their girlfriend won't try anal just need to be "gay for a day". Men are queueing up on Tinder and other apps to offer themselves. I can't see any biological reason why arses will feel different based on sex.
Replying to @anon_opin@mastodon.social
But there's so much more to sex than just the act of penetration.
You're addressing men who have girlfriends but can also get it up for another man (so: bisexual men), who want anal sex and can't get it at home, and whose girlfriends are also relaxed about them sleeping with men outside the relationship. That's a pretty small constituency, wouldn't you say?