That sounds like the majority of ntr I've read.
Hmm.. it seems like ever other NTR I come across, it's an elderly gentleman or overweight person (to use the politically correct terms) doing the stealing, and a lot of times it only really becomes consensual at the end, after the girl had been forced upon and convinced that the sex with that person was worthwhile. And usually, even when the small penis/premature ejaculation aspect is incorporated, it's very minimal. One manga that pulled off the humiliation of sexual inadequacy very well was
this one, which I suppose is a masochist thing, but there's only really two redeeming pages, since the guy that steals her away isn't really attractive (just his dick more or less). There was one, however, with a really hot pink-haired girl (that I can't remember the name of), where the stealer really is both well-endowed
and attractive in every respect. The MC is not only cuckolded, but he loses his girl in the end, and it's really sexy.
That's the better kind of netorare, because it's not about a guy breaking her from without, it's most about her coming to real terms with her inner whore and her entire worldview and persona changing to fit. Basically it remains her choice, so she has agency, even if it's for "moral degeneration".
Exactly. It's the most soul-crushing form of betrayal possible, since, as you said, she has agency. It's more than just ragebait. I think it's called Netorare Type A, but rarely is netorare subdivided into such genres on most websites. Rather, it's lumped all together and you have to comb through a lot of.. let's just say unsavory stuff to find it. Part of it too, is since I'm more drawn to mangas that I can relate to, I go more for the "girlfriend" than the "wife" stuff, since the characters are more in my age range.
My dream netorare would contrast bad sex scenes of the MC, showcasing the girl's dissatisfaction with his size and/or sexual performance, with sex scenes of the guy doing the stealing blowing her mind in bed and her commenting on the fullness, stamina, etc. The MC might be a sweet, sensitive, insecure guy and the stealer some confident alpha jock (though it's certainly not required). Both preferably would be attractive, but the stealer would have all the goods and then some. I don't know why I like the guys she has sex with to be attractive, too (even if one them is a complete failure in bed). I just do. Haha.