First I will define what netorare and netori are.
Netorare is more focused on the humiliation of the MC, this is the focus than a simple cheating and cuckold, the MC is always shown as not having the ability to satisfy his woman sexually, added to the fact that he appears more fragile and his penis is small, during sexual intercourse there are always lines to belittle the MC and praise the toro, it is more of a fetish of sexual domination of the Toro over the MC through the woman, and it is very common to reinforce this with kisses of sperm from the Toro and other situations.
It's not simply stealing a romantic partner, it's not like the wife meets someone else, falls in love, and ends the marriage.
Usually, the ending of these games is that the wife becomes a sex-addicted slut and sleeps with anyone but the MC, but they end the marriage.
Netori = is the netorare with the characters exchanged MC is Toro and the NPC and the cuckold, but do not confuse it with a love dispute the objective is not to form a romantic partner with the LI but a sexual one while she maintains the relationship with the NPC as husband or boyfriend.
He doesn't see Li as a romantic partner, a girlfriend, or a wife. She's someone else's, but his slut, his sex slave, his prostitute. Reinforcing this, the MC doesn't see her as a woman, but rather as an object, and she knows this and will do anything to have the MC's dick.
This doesn't preclude the MC from having a girlfriend or wife who is faithful to him. She even appreciates that he does this and feels valued by treating her differently, with love and affection.
Netori is not the theft of a Li for the arem with a loving relationship, this is a love dispute.
Few, only stories and comics, the best were Korean. Only two games explored this mechanic, and it was a lot of work for little reward. Others start with the mechanic but quickly turn into romance; the cuckold doesn't even appear.
For me there are a series of factors, firstly, they don't really understand the fetish, who creates it and who plays it, another reason is the lack of good games to popularize the theme and create a base willing to finance it, another reason is that the game will be attacked by the "Mother Virgin", No-NTR, Cuckolds and Harem.