My 2 cents on the issue that blew this thread:
Lazy, writing. The end scene is based on who you picked, meaning, one decision mattered, in the whole game, 1. Worse than that, the one you pick is the one that ends in said scene, which is simply moronic. Tamara showed to be smarter than MC so she should have understood there'll be no end to the blackmailing, even commented about preferring the 5 IQ guy than the antagonist. Jo, although helpful and innocent, even selfless, looks to be way too involved with the MC as the first choice to do something like that. Maybe if he had spilled the beans to her and wasn't the first choice, thus, wanting to protect her sister and MC, I could get behind that although I personally despise NTR.
Instead, we have an idiotic scenario that doesn't make sense and is designed to raise angst in the player for angst's sake. Also, I feel the MC is losing IQ at an astonishingly quick rate.
For many other reasons others have already pointed out, the tag is appropriate at this point, while it might have been debatable in the past (since the MC didn't actually go out with anyone or the girls in question at that point) it's pretty solid now. Whether there should be a distinction for emotional betrayal, or "about to" ntr, the lack of explanation and way the cliffhanger was presented, that's the intended purpose. Thus, at least until said cliffhanger is resolved in an appropriate manner, the tag should stay.