I think once again, NTR writers are writing some ugly ass antagonist in the game as someone to steal the wife away. I wrote this a few post ago, but damn writers need to put themselves in the shoes of the woman.
Imagine if you were a woman, and your husband of many many years wants you to fuck his ugly ass boss. You say "fuck no". Then maybe you do it because of blackmail/coersion/wanting to please hubby. W/e. But you do NOT fall in love with his "massive dong". That just does not fucking happen EVER in real life. Sex is a lot more than a big dick. Love is a lot more than good sex. Love is about emotional support, comfort, and really finding a partner. The writers MUST employ tactics that display the antagonist winning the girl using those tactics. A combination of good sex, emotional connection, and display of partnership is what will do TRUE ntr. Sure, the sex can be good. It MAY be addicting. But like all addicts, the guilt and revulsion will come. All writers miss this great opportunity for inner dialog. The guilt, the self pity, the degradation of pride, etc. It's all very beautiful and deserves its own scenes.
After realizing this fact I cannot enjoy most of the NTR stuff. Sure I still play them and jerk off to them, but it just feels slightly missing and unrealistic.
Here is a much more realistic scenario that I've read from Reddit's relationship_advice. The woman starts seeing some other dude. First it was just texting / flirting. Then it becomes physical. She still very much loves hubby and the family they built, but her lust wants to be satisfied. She's not anyone's "bitch", but her own master in wanting to fuck other men. (Now, she could be blackmailed or whatever, but there just wouldn't be any love from being force fucked, even if she orgasms)
Now, the hubby has to display degradation in his ability to provide. Maybe he gets sick. Maybe the antagonist is another guy at the company and does a lot better than the husband. Sure, you can write the small dick big dick in there too. But you have to include a lot of other, non sexual things that makes the antagonist objectively better than the guy. THAT's how real relationships fall apart and how real life NTR happens. Maybe you can add flaws for the husband too, like easily jealous. Not trusting wife. Promising to stop drinking but still drinks, etc.