tldr available at the bottom

One of my best guy friends says sex with his now fiancée is not the best. I don’t know too many details, but she has a condition that sometimes makes it very painful to have sex, even having to stop completely, so he has to be very patient, do a lot of foreplay, thus resulting in not being able to have quickies, sex in spontaneous/risky places, and rough sex, which he particularly enjoys a lot. He says it removes some of the excitement. I know he has cheated before, and has found way more enjoyable sex, but now that he’s engaged he’s determined to remain faithful.

As a woman, I find this super sad because if he’s unhappy sexually he will most likely cheat again. Also, I’m single, but I find myself thinking “what if my future husband is not satisfied having sex with me?”

How do you live with something like this? How can one have a successful marriage? ——-

tldr; My best guy friend (I’m a woman) is marrying someone who he has cheated on because he is not satisfied with their sex life (she has a medical condition and he likes rough sex). He has even cheated, but is determined to remain faithful now that he’s engaged. How can one have a successful marriage despite having an “okay” sex life?