Although I wouldn't call it NTR unless Sam was supposed to be in some kind of romantic relationship with Jack. Currently Sam's interest in her seems to be decidedly unromantic. I don't think he would care if others were fucking her as long as he gets to hit it as well.If you don't want to get NTR'd you prolly should look for another game as there had been more than enough hints that this will be most prolly the case.