With all due respect I kinda disagree with this. From a Christian perspective, a lot of them have guilt complexes when it comes to married or unmarried sexual behavior, especially in the evangelical community. Many wait till marriage because they’re scared that it’s sinful if they don’t. Some will decide to be celibate (even if they weren’t before) once they become dead set in their faith, or by Christian terms “born again.”
I’m not saying that sexual activities can’t be used for manipulation, obviously they can. But knowing the attitude Christianity can have about this stuff, I’m trying to give her the benefit of the doubt. OP should see a couples counselor I think, and then decide where he wants to take the relationship.