I set the NTR to "optional," and encountered 2 options thus far.
First, bitchy girl you've talked to once starts femdoming a nerd boy. Game gives you 3 giant blaring warnings like, "are you sure you want to watch this bitch that you might fuck at some undefined point in the future give nerd boy a BJ!?! Are you
really!? Are you ABSOLUTELY sure!?!?!"
Second, some asshole jock tells you he wants to start hitting on your sister/cousin that you've been working on for awhile. Game lets you control what he tells her, either hits on her, or compliments MC.
You can also set NTR to "OFF" and it will automatically select off these options without even telling you it's even there.