I'm in no way qualified to judge what counts as believable psychological manipulation, certainly less so than the average person. But yeah, there's no shortage of games where I know what I'm reading would never fly IRL, and when it comes to the corruption theme that pretty much ruins all the fun. I'll just go over my favorites in this subgenre and see if I can find something in common between them.
Karryn's Prison - MC has a massive, monstrous libido that she represses as well as being thrust into a situation where it's put to the test every day. The corruption here is in the player's hands, so it's up to create your own corruption arc, if you want one at all. About the only thing that's unavoidable is she discovers her sadistic side.
iNSight of you - A corruption arc focused on orgasm denial and blackmail. The more I think about it, it's very different from standard corruption game tropes - not just in the methods used but in the target character, who is a rather extreme personality. It's more focused on revenge, explicit degradation and domination than most other such games. For me, this is not a game about turning a prudish nerd into a sex fiend, or about breaking social taboos, it's about watching a hateful rich bitch lose everything. The writer plays to that very well.
Witch Trainer - Essentially a game about grooming a naive young adult by impersonating a trusted authority figure. In all honesty, if written straight, this would have been all kinds of creepy. Thankfully, the comedic writing sells it, making it one of the most enjoyable ero-games and a solid corruption arc.
Slutcraft - Well, it was one of my favorites until I realized how much of a role Stukov would play. Until then though, it promised to be a less verbal corruption game, where the alien environment itself would be pushing MC's sexuality, with very believable reactions from the MC. I'm sure newer updates continue on this theme, but the presence of a standard-issue perverted maledom is bound to spoil it for me.
Ruin Me - A unique case of the corruptee explicitly asking to be corrupted, with a focus on BDSM. Arguably the best-written game I've listed, though very different in tone. Hard to tell how believable it is - it's set in something like the 1900s in some kind of alternate timeline with much more permissive views on sex and gender. Oh, and Lovecraftian supernatural entities.