During "Get Past Granny" you can choose whether Mia is fucked by a werewolf the first time she wears the red riding hood outfit. That's the only 'warning' I can think of.There used to be a warning in the game, I don't know if it's still there.
Flood69 How much there is depends on what you count as NTR. Some people count any time a LI gets it on with anyone who isn't the MC, full stop. Others look at circumstances & motivation. Some don't count stealing someone else's girl as NTR. And so on. PhineasFlynn gave a good list of what might be NTR depending on how you define it. But, yes, there is no single switch for it but you can avoid all of it. Be aware, some side LI storylines *require* NTR of some sort to advance them...avoiding it means not pursuing them, or not advancing the storyline past a certain point...