Happened the same with me. ANd my wife encouraged me to do it. Started with eating his cum out of her hole (which she really enjoyed). Then progressed to fucklicking (licking her clit while he fucked her and him rubbing his cock and balls on top of my face. I posted some stories about our journey down the perverted sex on my profile.
The best part is at the end when the guy fucking the hubby's ass cums violently and pumps his seed deep into hubby's willing submissive body where it belongs and will do the most good.