this is a happy ending! Yey!
You haven't solved the disappearance of LXT! You separated them and now you separated YY from his master and they even haven't had a proper long discussion at the very least!
Yi Yun seems to take for granted LXT. Not sure if the author forgot but the author made it worse by throwing FMC material here and there at Yi Yun. It wouldn't taste good to me if this ever becomes a harem just because an fMC material sprouted like mushroom here and there.