The weekend comes and it's a college campus. The issue with rape is who has the power. There's not a lot of women going around raping men, because rape is about power. Mechanics will tell you that it's the man. Also, this is where perceptions of sex come in to play.
Women can see sex as a form of recreation, procreation and violence and perceive it in that manor.
Therefore with a woman, often sex with someone she loves or is interested in could be enjoyable, but having the same thing happen against her consent is perceived as violence. And it's doesn't matter whether the man thinks she wanted it or was flirting with him. If she wasn't in her right mind, or said no, it was rape, or you've just put yourself where she could see it as rape. Maybe that girl that was drunk at the frat party last weekend really did want to have sex with you, but I wouldn't always take that risk.