I think I like the idea that Kirito gets off on watching first (voyeur, since he peeped on so many other couples fucking in part 1) then gradually gets to the idea that "what if Asuna", which is another kink but complete taboo that Kirito can either reject or accept. Then eventually, Inoda catches Kirito peeping (either on him or some other) and starts giving him small glimpses of what he's doing with his partner (Asuna).Yeah that's basically the process I would see happening if it could be implemented, it just adds some depth. I don't like the cuckolding value increasing so I would probably split that between two options if someone wanted to increase that value though, same with the anxiety part of the process value increasing. There were some choices earlier in the game where Kirito chooses between peeping/ not peeping, and questioning himself whether or not he believes Asuna would like or wouldn't like/ be like this (public sex) etc. Those options should increase the values of Anxiety or Cuckolding depending on what you choose.
Personally I would only increase the Anxiety values and keep the Cuckolding values as low as possible. An oblivious cuck is more erotic appealing to me than a cuck who suspects something & gets off on watching. When I see the tag "NTR" (for Netorare) my sole focus on the kink is that the Significant Other is STOLEN (as per what NTR is defined for) rather than just basic & boring cuckolding kinks. It's hotter when the Significant Other is coerced through slow gradual corruption (and/ or blackmail) to eventually enjoy cheating and being stolen from his/ her lover. For me, that aspect makes the possibility of "Revenge" a lot more likely. How can a willing cuck make the revenge arc work kink-wise if he enjoys being cucked? Makes no sense to me.
edit: It'd also make sense for the Anxiety & Cuckolding values to increase by Kirito calling Asuna to confirm where she's at and suspecting that something is going on when he hears noises (increasing cuckolding value), and when the location Asuna says she's at doesn't line up to where she actually is the Anxiety value increases because she just lied to him.
I just think there needs to be a vehicle for Kirito to have some reason to believe/consider the bad thing happening to him. If you were to play this from the Kirito POV for the treehouse scene I think you’d literally be clueless if not for the door scene basically. So being able to go and confirm her location is okay. Maybe in game, admin gives him a “buff/debuff” in that he knows exactly how Asuna feels at the moment. But it’s up to his imagination to fill in the blank why she’s horny while with Inoda. Paranoia/cuckold mix and creates the “idea” of what’s going on which is the exact scene we saw previously.