"Humiliation", yes, without doubt, but "jealousy", seriously ? What the fuck this word do here ?
Take
Swing & Miss, by example, since it's one of the well wrote NTR games. There's desperation, feeling of humiliation, and all the negative thoughts that you can imagine, but not a single time the male character is jealous. Simply because it's absolutely not part of the fetish.
The main character of a NTR story can not be jealous, principally because he's either blindly in love (and so think that it's just a phase, that she'll come back soon), or think so low about himself that, for him, he deserve to be treated like this. Both being states of mind that prevent him to feel jealousy.
Anyway, if he was able to feel jealousy, then he would fight back, or at least try to. Therefore, the story wouldn't be a NTR one anymore, but the story of someone who's trying to win back the love of his life.
There's also the variation you can see in the last update of
Chains of Pleasure.
The client is a perfect cuck, and a happy one. His wife is somewhere outside, being fucked hard by some guy(s) and filming it for him to fap later. This while he's at home, faping while watching a married women being fucked to unconsciousness, by someone who isn't her husband.
He feel humiliated, it's what trigger his desire, but how can he feel a single once of jealousy ? He want his life to be like this. He want his wife to fuck with anyone she want. He want her to film it and give him the movie. He live the life he dreamed to live, he have absolutely no reason to be jealous...
I gave you four of them. They all are real reasons, and part of the NTR lovers fall on one of them.
Yet, you preferred to not acknowledge them, answering according to your thoughts on the subject, and not according to what was effectively wrote. Like you did, more or less, for any valid reason(s) gave by others.
You'll go nowhere like this. As long as you'll not be able to go outside of your shoes, without necessarily needing to be in theirs, you'll never be able to understand what can appeal them in a NTR story. Mostly because you'll stick to your misrepresentation of what NTR is.
But do you effectively want to understand it ?
I mean, the example you constantly use is scatology... There's many disturbing fetishes. Urology, hard BDSM, handi-fetish (it surely have a name), guro, and so on. But no, the only one you use as comparison is the one that isn't just disturbing, but also disgusting for whoever don't have it.
therefore, it look more like you want to be proved right, than have your mind changed.