It's sad that this is often true.

I once had a buddy tell me he was struggling with finding good quality sex with women and he's reminiscing about the times he had good sex. I told him if he wasn't having good sex it's because the woman didn't want anything from him. His brain did some mental calculations and had an epiphany...

Sadly, a lot of women see sex as a means to an end so if there's no end for them to gain from you they aren't interested in the sex.