im sorry but you are literally doing a false comparison, so if the story isnt focused on the guy like a lot of them arent it isnt ntr? from what youve said it seems like that, but ive read plently of ntr that have the guy not knowing at all, so they arent ntr?
If the guy is in the picture, it's NTR. The NTR reveal is the bread and butter of the genre, but not strictly necessary. If you're reading a story of, say, childhood friends, and the boy likes the girl, then the girl starts sleeping with a third guy, it's NTR. If the guy finds out and is hurt, it's a harder NTR story. But, and you need to pay attention here,
you just need A to like B, and B to sleep with someone else.
If they're in a relationship, then all the more dramatic. If he walks in on them, sees what's going on, and goes to his knees crying and jerking off, then all the more dramatic still. But the entire story could be about how the guy sits around pining for her, and unbeknownst to him she's getting plowed in the next room: it's NTR. She could positively hate his guts, and be doing this to "punish" him without him knowing: It's NTR.
the term is literally translated be taken off, if there was nothing to be taken from i genuinely dont see why it would be called ntr.
You're running back to "NTR=Cucking" which is the most wrong interpretation possible. You
do not need a relationship for NTR.
The most I've seen is stories being tagged with "Cheating" and only "Cheating" when the person being cheated on is only mentioned, or isn't brought up. It's technically inaccurate, but I can respect the distinction as a practical one. But that's it. Any other case you see where there's a guy in the story, who at least likes the one getting plowed, is NTR, and should be tagged as such.
If you read all of this, and it doesn't bother you, then congrats, you're not nearly as bothered by NTR as you think you are, and you can probably take the tag off your blacklist.