Im assuming that og Sera returns after the situation w the bitch is resolved and the grandma shaman throws hands at that Pennar shaman dude or something along the lines of that
I've thought of that idea as well, since who Ro un liked was actually Jia not Sera, while Jia also liked Ro un back.
And Jae eon realized his feelings for Sera, who had trully loved him. Sera actually had such a nice personality but all that curse from Seongyeong disturbed her mental and physical health terribly, otherwise Jae eon would've fallen for Sera long ago.
Yes frr
Wait hear me out but what if Jia goes back to her real body and gets engaged with blue haired dude and then Sera's body returns back to the original and then she gets re-engaged with the fake fiancé guy (since we've seen how nice she actually was before meeting that btch and how he regrets losing her).