Well, it is normal. Me and my gf (even though we started having sex less then a month ago), both enjoy playing "a game of rape". It may sound a bit strange, but she has the most powerful orgasms when she resists me. And it is not like completely simulated, I have to use force to get to her, and she fights off.
As a result our bodies are always covered in bruises and scratches, but truth to be spoken, sex is just amazing. With my previous gf we didn't have anything like that, it was just regular sex with tender kisses and we only did it in like five poses and only at home. I didn't enjoy that very much. It was one of the reasons we broke up.

I believe, that it's okay to have fantasies or even actually "rape" your partner, but on;y if he or she doesn't mind