Most if not all of it falls under netorare, not netorase. Rowan is generally aware that the Twins want to have sex with his wife, but isn't aware of any specifics and I think at best views it as something that he doesn't have any real power to prevent. (Note for others reading this: Not to be confused with the player not having the power to prevent it.)
I suppose Greyhide content might fall under netorase? But while I haven't done that content myself, from the outside it seems like that content is more of an open relationship deal with someone they both like (potentially sexually for both of them) than it is Rowan getting off on Alexia having sex with someone else. Hopefully someone who's played that content can give a bit more info there.
The one explicit incident of someone being aware and into it is a female character who gets off on Rowan having sex with other women in front of her. But said character isn't a protagonist, so it isn't technically netorase.
Netorare: 95% of the NTR content in the game is Netorare.
The majority of the netorare content is Alexia x Twins from Rowan's PoV.
Maybe Rowan x Hel or Delane from Alexia's POV? Delane seemed to be kinda set up to be a romantic competitor for Alexia, but Delane was sort of
- so I'm not sure.
If you sub to Cilonia this might also lead to netorare from Alexia's PoV- Cilonia seems.... very possessive.
Maybe the Twins x Rowan NPC arcs will have a Netorare pathing when they are written as well. Currently Rowan x Twins is a cheating vibe instead of a Netorare vibe.
Netorase: 2 scenes, 4 if you are being generous with classification
Greyhide): I haven't played the GH route in full- but there are two scenes that you could call Netorase amongst them. 1 for each of the MCs POV. Everything else in the Greyhide arc is just open relationship, poly relationship, or cheating. (Though a bunch of the events are still kinda written to reflect the Netorare framework they originally had)
Helanya): If we count a NPC cuck-queening for the PC as netorase Helanya has two scenes for it. (One with Liurial and one with a Castle Maid).
Looking forward to more when Winter works on the arc later. Cla-Min + Mini x Rowan x Hel would be delicious.
Netori: Maybe later?
Shaya): You could argue that one side of this route is headed for Netori. Won't find out until act 2.
Other potential Netori targets that would be fun):
~Alexia steals Mary from Jezera
~The MCs steal Zharia from Andras
~The MCs steal Indarah from Jak