I see this question get asked a lot on NTR stories. Personally, I think it should stay. The point of NTR these days (I've said this before) is to steal away the other lover in a sexual manner. I think this feeling can be achieved even when the two are not formally in a relationship. It's certainly less painful than stealing away an actual romantic partner, but I think if anything this just means that NTR has various levels of intensity, with this being one of them.
I think most people would have gone to the event if they got a chance to bang their crush as normally you like the idea you have of a person and not the real one. Everytime I had a crush the person started to annoy me as soon as I seeked contact with her and started to know her better...