It's pretty common for women not to get wet from what I have heard. That's why it hurts them so much. The brain is what controls the body so I think if what is going on is really that bad your brain is not going to be sending signals to get ready for sex. More than likely your brain is going to focus on pumping you with adrenaline in hopes of fighting the person off or running away. I have been turned off by someone and when they tried to stimulate me nothing happened. That is not nearly as bad as being raped either. If stress can cause you not to get it up then how come being raped won't do the same even though it is a lot more horrible than stress.