Actually gf/wives will more likely to take it in the ass by lovers then husbands!
Many wives wont let husband go in their assholes but when a lover asks for it (according to my wife) they get excited about the idea, pleasing the bull and letting him enjoy their tight hole as they be more willing to want to try feel their cocks in it. Its kind of the hornier the wife/gf for the lover the more likely she will want him in her ass.
My wife naturally likes her asshole fucked and cums best getting it in her ass. She almost always asked me to do her ass for a good while after we got married
now she prefers her lovers fuck her ass, I think everyone she fucked.. had him do her ass in the first couple of times.