Also wanted to add that during my time as a swinger and Bull, I was lucky to have answered ads for couples looking for a male to fuck the husband or boyfriend. Those experiences were intense and some guys were unbelievably tight! I didn't last very long, especially when the female was involved. Usually got to fuck the female afterwards as a bonus. Oddly enough, the guy was often the better fuck of the two.
Quite a few women have a fetish for ass and anal sex but because of puritanical societal mores and guilt promoted by certain institutions, most suppress those fetish urges. When you can find a woman who hasn't any nonsensical preconceptions or hangups, she's often a keeper. This woman may have discovered that she can feel his penis grow even bigger when she inserted the dildo into his ass. That's something we Bisexual men know (or should know) and honestly some of the most powerful orgasms I've had in my life occurred while getting sucked and fucked simultaneously. It's a beautiful, intense, full-body orgasm that runs up and down your spine.