I believe she has already made this point very clear in the very beginning, the second day to be precise:one of the girls had experience before meeting MC and considered that NTR because it was not only implied but also mentioned in dialogue. If that does disturb you as well, that would indeed be a problem, but as somebody who generally dislikes NTR I would say I have no problem with this. Especially because it is not NTR at all in my book that characters existed before game start.

And more than once in fact:
