Achtually!
Well, as far as i know which is not very far, anykind of sexual intercourse of a love interest that does not involve the main character is considered NTR
around here. So with that very wide definition, the flashback scene of Hana with the singer at the beginning of the game might very well be considered NTR. Much alike, every time Kathleen or Killian is sexually involved with a carnation, it might also be tagged as NTR since there is somekind of a love route for each one. It would even be hard netorare since they are more or less blackmailed into it(Felicia apart).
I'd like to add that i love the game as it is and am not asking anyone to change anything to it.
The creators probably chose carefully which tag to put, and i totaly understand why they did so.
What i do like though is watching the world burn
