>>8423293I think a large part of it (so to speak) is that the reason netorare/netorase/netori's erotic appeal is the humiliation and the submission/dominance aspect of it and the cucked party has their ego, their pride, their masculinity destroyed because they are mentally and spiritually castrated in the act of being cucked (remember the woman typically denigrates their worth--or more accurately, their lack thereof as a male between sucking/fucking her new bull).
Of course, when it comes to hentai doujin works it also makes more or less sense with the protagonist's canonical personality for example in FGO Ritsuka Fujimaru is canonically a huge schmuck as a Lawful Stupid oblivious dumbass who never doubts anyone's intentions so they get blindsided frequently by new people betraying them to the point Pepe had to frequently remind them they were still enemies technically even though they temporarily had similar goals in the Indian Lostbelt and avenging Kirschtaria's literal backstab against Beryl.
Mashu herself has canonically been susceptible to NTR situations such as Fionn proposing marriage if she lost to him and Diarmuid in the American Singularity of Part 1 and then, Kinoku Nasu himself wrote the NTR scenario of her getting amnesia and marrying Boggart the furry white lion faerie while LARPing as the "Child of Prophecy" even after he announced his intent to rape her and once she instinctively defenestrated him she seemingly forgot about that and offered to give him back rubs and such in the Avalon Lostbelt meaning that he has sanctioned this genre and actively promotes it since Type-Moon originated as a doujin group well-versed in otaku culture.
Black Bart also has an obsession with her due to her "Peek-a-Bangs" hairstyle as his most prominent personality trait and even has a creepy miniature of her in his room due to said obsession.
