I can assure you it isn't. The closest is netorase on the route where Riley confides to Mike, and the Dev should definitely wait until this is added as a possible tag and not add the netorare (ntr) tag as Devs were forced to in the past. As has been indicated, cheating only becomes netorare, if the protagonist is the victim. It doesn't matter whether the player erroneously feels like it should be, because they self identify with the men who a female protagonist cheats on. That still doesn't make it netorare.
And you obviously haven't played most of the games here, because quite a lot of them really are NTR, and you really would have hated them far more than this one, if you're finding this one too much. There are plenty of games where the male protagonists are ruthlessly humiliated by their female LI's and don't remain utterly oblivious, as happens to Mike in this game on the cheating route.