idk guys, im not in for NTR stuff even if is softcore like this (they dont even have a relationship) but getting cucked (mentally) a meter away is wild, i'd give this manga one more chapter or even 2. If shes indeed rawdoggin dudes then the story must be soo good so i can keep readin this shit lmao
Some consider BSS (Boku ga Saki ni Suki datta no ni / Even Though I Loved Her First) to be NTR while others do not since there is not a two-directional love relationship that gets broken. I would say it is NTR if the FMC gives up on the MC who never makes a move, and not NTR if there was no "that way" attraction of the FMC for the MC in the first place. (Roles can be reversed of course but it is usually it wouldn't be the MC giving up on the FMC making a move.)
In this case I don't think that the MC
at least knowingly has romantic feelings for the FMC. He DOES see her as an sexually attractive woman but views her as his older "sister" as he did as a child. I think that the FMC
does have romantic/sexual attraction for the MC.