what exactly hurts?? Does she say it feels like you're banging into something?? If so that is the cervix, and unless you're hung like a donkey she's got a curved one. My G/F has a curved cervix and I hit it alot, you don't have to be hung like a pornstar to hit it either. It's actually kind of a good thing in a way, if she's properly warmed up, hitting the cerivx will actually force your cock up into the area where the gspot is. But if she's not properly relaxed and aroused, it will hurt her. Now if it's a problem with inside walls of her vagina.......than 1. your cock may be coke can thick or 2. she's got lube issues.