
Ah, hey. Well, I kinda simplified what I said before, and wrote what generally happens in those type of manga. The manga I was reading was a bit different, it's about twins who swap, and here it is if you're still interested: http://www.mangago.zone/read-manga/kobayashi_ga_kawai_sugite_tsurai/
I'm sure if you looked through the school life/gender bender tag, you'd find a lot of what I first wrote, cause that's where I got the idea from. Sorry if you had your hopes up UwU

i'm quite addicted to gender benders so i've read quite a lot but so far, i encountered no plot twist like that. the only one that is a little bit close is http://www.mangago.zone/read-manga/ng_life/ i was always cracking up about how the main guy is always disappointed that the reincarnated form of his beloved wife is a guy and often suffers from it. later, a girl that looks exactly like him (not a twin) appeared. he did not end up with both tho.
also, if you're a fan of those stuffs like me, i think you'll enjoy my fake bl list http://www.mangago.zone/home/mangalist/45645/
I was reading this story where a girl dresses as a guy and sneaks into a boys school, eventually falling in love with a boy and him with her, without knowing she's a girl. I've read quite a few like this, and I was just thinking, what if one of the guys were just gay, and ended up disappointed they were a girl. that would be a nice plot twist for once. O.O