A scenario that is both arousing yet deeply disturbing to me is when the MC experiences a taste of womanhood through a temporary method, like bodyswap or VR. Whatever the catalyst, this irreversibly alters their psyche, to the point that they want to make the genderswap permanent in order to keep feeling the same sensations (or maybe they just turn gay or something). Often bundled with corruption/mindbreak
Let me know if you have any more to add

nhentai.net/g/521556 - Juunishin Tiger Red ~Otosare Yuganda Seigi no Yukukata~ (Body Swap)
nhentai.net/g/51678 - FARFALLA (VR)
nhentai.net/g/268393 - Aisei Tenshi Love Mary (Sensation Sharing, starts around p.117)
nhentai.net/g/437755 - Kitsuneko Miko Ichiya Taiken Course (Skinsuit, detable inclusion)