Okay, here goes.
What happened is that zhen hao's wife's body got merged with her dad's (mr shen) during the wedding because of the weird phenomenon that was explained in the previous chapters (thunderstorms). Whenever there's a trigger, they will switch bodies with each other— one is never at the same room with the other anymore and what the dad wears, the daughter will also.
In one of mr shen's appearances, he turned back into his 19 year old self and we discovered more to his and his daughter's story (like how zhen hao and her only married out of her convenience, and how it seems like mr shen had feelings for the girl's biological dad etc).
Basically summing it up, they ARE switching bodies— i know how it's confusing because it's been awhile since the girl appeared. But well, it's not a mere delusion/hallucination by zhen hao. No, zhen hao is not marrying mr shen (yet?? idk).
an easier explanation(?) hehe;
. zenhao and the girl (fu) are married.
. fu is actually the blood daughter of fu xiao (the red haired guy who died while racing, also mr.shen's schoolmate and dearest friend)
. mr.shen took fu in his care because ofcourse her father and he were close friends.
. mr.shen and fu switch places when fu and zenhao come in contact, even a little touch.
. however they(mr.shen and fu) can actually also come back into their original places if mr.shen sneezes (up until now thats the only way we know)
. since they only switch places and not clothes, mr.shen transfers into fu's clothes and fu into his clothes.
I’m fucking confused so is that the Daddy that he’s marrying or did his girlfriend switch bodies with his dad or did they just switched clothes and now he’s marrying the daddy or like in his mind he sees his girlfriend but that’s actually the girlfriends daddy????