Hi delish, good point on the meanings of ‘betray’. You have made me reach for the dictionary, which is always good.I guess this would be ‘betray’ in a sense of ‘react in a way I don’t want’ (as opposed to an unrealistic ‘reveal what I really want’).
I think that’s part of being human. Whether in a life-threatening crisis or under more ordinary circumstances, human bodies tend to react in all sorts of ways without waiting for approval. I think I have encountered the ‘body betrayed’ phrase in connection with exhaustion, sickness, the process of aging, stuff like that. And nobody, of whatever sex, orientation or fetish decides to get aroused by XY – it happens. (See Sadism.) We don't choose how we react to stimuli. But we choose what we do, which is why real rapists and abusers are responsible for the crimes they commit. Personally I have found it somewhat disconcerting at times how arousing I find nc fiction, usually with descriptions of men who get subjected to sex against their will. But, as neither the writing nor reading causes real suffering to a real person, I choose to indulge in this genre for enjoyment.
A resource for authors: the wikipedia article on Rape. It even contains a note on the 'orgasm ≠ consent' theme. The 'fantasy vs. reality' theme also shows up in this article. Authors may wish to peruse the section on ‘Profiles’; it could be helpful for constructing realistic rapists.