If a woman says "I don't want sex, but..." anything after the but is irrelevant, she doesn't want sex and you are about to rape her. Obviously it would be immensely difficult to prove, and if she follows it up with "oh go on then" it looks like you are in a bit of a grey area - but it's still rape because she told you no, and you know she means no.

I know the article is closer to scenario 2 (although not exactly, the article states that violence wasn't used), I'm demonstrating that there are scenarios which are different, ones which are more complicated, and that there are reasons for other terms to be used for different versions of the "same" offense.