You just hit on one of the primary issues with "NTR" it is the label itself - lumping everything in the Infidelity genre under NTR is just ignorant, and let's not start with the idiotic conflation of Western 'cuckolding', 'sharing', 'swinging', etc. and the Japanese 'netorare', 'netorase', and 'netori' - are there similarities? Yes. Are they the same? No.
If you decided to make the game/story I'm all in