Probably a dumb question ** trigger warning

I have a question about rape. And when I ask this I promise you in no way am I blaming the victim. I want to know because usually when one is raped they are not wet due to all the factors being scared, trying to get away, etc. So I want to know, like I said I promise I’m not blaming the victim this question just makes me wonder, why do rapists enjoy “raping” if it is often dry? Wouldn’t it physically hurt them both?