Again it is a game that is selling a Fantasy. It doesn't have to make sense. Because if you open up that bottle have fun never playing a Game or watching a Movie again.
It is a "what if..." Scenario that you should just embrace and experience. Now of course you don't have to like it if it is just too much for you in terms of not being realistic. You can also then personally just say to yourself, that it is instead like x if it makes it better for you.
But at the very end of the day if we are just taking what the Game is setting up, then everything sexual happening to Karryn happens with her consent. That is just a straight up fact no matter of how you want to spin it.
Even fantasy and science fiction has their limits about how much bs they can pull before they hit
my "bullshit" bar. Besides
my own bullshit bar, they also have to be coherent in their own settings.
I believe prisoners in karryn's prison would take advantage of her 100% of the times when they see her lying on the ground naked and they certainly would not ask her consent. These prisoners are the same people who masturbate to her on sight, even if she is fully clothed and holding her halberd ready to attack them.
Edit: But yeah I agree
technically there is no rape in the game. I'm just pointing out it looks silly when you manage to look past technicalities such as desire system.