I think we're moving away from it as a society now but certainly when I was growing up there were lots of mixed messages when it came to rape and sex.
Sex was quite often portrayed as something men enjoy and women do to keep men happy, espicially in long term relationships.
Men that have sex with lots of women were seen as better, there were loads of sceens in films where men went to a party and there were loads of drunk girls and the men saw it as an easy way to have sex. It wasn't something that was hinted at as wrong, usually was played for laughs or was just excepted as part of the story line of how men behave.
If you've grown up with these kind of messages then you're at a party drunk or in a long term relationship and end up having sex when you don't want to/haven't consented then you might not think of yourself as being raped. Just like if your a man and you pick up a drunk girl/have sex with your partner when they're not in the mood you might not think of yourself as a rapist.
If we can find a way of giving women the power to realise what these situations actully are and make men realise that what they are doing is rape then isn't that a good thing?