If you are tired of the "save the maiden who is going to be raped" trope, good for you: I am not. You will be in the greatest difficulty to demonstrate that this trope is boring. One is responsible for one's own boredom, they say. To have a good ending, a bad one must exist. To win the love interest, one must be able to lose it, otherwise the acts have no reality.
On the other hand, I don't know why you are talking about this. That's not the point, NTR has nothing to do with a rescue and a priori nothing to do with a rape. In NTR you lose, that's all. Basically NTR and harem scenarios where countless females are inexplicably attracted to the MC have some similarities: in the first one you can only lose, in the second one you can only win and that's what makes their weak.
If the girl gets raped, it's not NTR as long as she doesn't betray you, NTR is the subversion of a female character. But again it's completely off-topic: Sunny won't be raped, and won't be conquered by another, the author was clear about that.