My favorite genre is definitely the NTR, but I've never been a fan of such scenarios where the MC is abandoned by his love at the end of the story, since this cannot be called a happy ending in any way for me.
Although the swinging isn't my favorite type either, where the both parties constantly cheat on the other without any remorse, relegating all kinds of emotional-bonding for each other to the background. I can't see any excitement in this, cuz I can't call such a soulless state a relationship at all.
The cuckolding is slightly better, actually I like that genre, but there you can fall into the trap that the MC is humiliated endlessly, and the game can easily move in a kind of femdom direction.
As for me, I would rather call the perfect NTR a mixture of the netorare and the netorase. A kind of "secret" voyeur-NTR, when the cheating happens without our consent, however the MC knows about the infidelity, but instead of stopping his girlfriend, he prefers to enjoy watching her "secret" adventures. At the same time the MC and his girlfriend don't start to drift apart emotionally, and this means when her adventure is over she return to us. lol
As for the SOD, I haven't seen the new NTR events yet in this game since I just started again from the beginning and I prefer building the MC's realtionship and his love attachments first ...but in the old events I also felt the Hikari's line too much and cruel. On the other hand, with Kirara, I liked the basic idea that the bloated ugly guy is after the pretty girl, just they messed it up as well in the end.
If I had to summarize the problems with the ntr at these two heroines, then in both cases it was mainly the third event. The both story was already exaggerated at that point, when the bulls humiliated not only the MC but also the heroines.
As for the other two heroines' events, Ichika and Anya's ntr story was fine for me. Or at least the old ones. I haven't seen their new events yet.