Since I am the authority on woman psychology, I will contribute to this thread. No time to quote all the people that need to be corrected.
Yes, women have rape fantasies. No, they don't have to be victims of some sort of traumatic event to have them. They are very common across all types of women. Why?
Obviously not because they want to be raped. Guys primarily get off on how girls look, smell, feel, etc. Girls, on the other hand, are far more aroused by their perception of how into them you appear to be. That's why the rape fantasy is so powerful. At the core of it, she is fantasizing about someone that wants her so bad that they have no choice but to forcibly get their rape on. However, the terror and humiliation of an actual real-life rape scenario will quickly cancel out any of that fun stuff.
As far as women being aroused by actual rape...of course it happens, but in that case I would entertain the idea of some sort of childhood sexual trauma. And even then it's probably extremely rare. What you rapists might mistake for arousal is just her body's natural reaction to a foreign object inserted inside of her (lubrication). That is just a self-defense mechanism of the female body to prevent damage. Probably something that evolved over years of ancient brutal rape history.
Alright then, carry on.