There is three main types (probably more sub-types as well): Netorare, Netori, and Netorase
Netorare is when the MC's love has sex with someone else when the MC doesnt want them to. The love interest either does it willingly or unwillingly, and isn't just limited to partners afaik, it can also be the MC's sibling, relative, friend, or parent, whoever the MC cares about, getting stolen from them.
Netori is when the MC is stealing someone else's love (again doesn't have to be partner), so they arent the one cheating, the other person is
Netorase is when the MC wants their love to have sex with other people (I think this one is similar to cuckolding but not sure how the japanese translates)
This is my understanding of the genre, so I may be wrong a bit, but for the most part I think its accurate.
If the MC of Deluded is not in a relationship/has a love interest, and is having sex with others, its not netorare.
If the MC is in a relationship, and is having sex with others without their partner knowing or the partner knowing but them disliking it, its Netorare.
If the MC is in a relationship, and is having sex with others with the consent of their partner, its usually Netorase, as their partner gets off to the MC cheating on them.
If the is having sex with a man who has a wife/girlfriend that isn't the MC, that is Netori, she is stealing the man from the other girl.