I'm honestly hoping on an ending where you can stay with your chosen girl, or well romantically involved with your chosen girl and all the girls staying, that would work too. But if you think about, most don't have a reason to return.I wish someday my MC will be able to tell Rae, that he loves her, she is such a bae. Or even in the ending, when everyone can leave the house, she can stay on earth with him.
I mean Cait is probably hated and wanted in her entire world, Naomi had a crew but her ship was destroyed when she was almost eaten no? Probably her crew is dead, Lyriel is an exile and that's why she was staying with her aunt and she does have a good relationship with her and the maids there now, but the thing is she can essentially visit at any time and for as much as she likes once the MC masters his power. Yona, I am not sure what happened to her, did her soulmate die? He family? She might return for revenge but not sure if for much else. And Rae, she was clearly conflicted about how she likes staying with us and seems to slowly grow tired of her old life.
Though MC's powers also open up new possibilities, with Rae for instance, her people have been in a though spot because of the past so I could see her superiors actually ordering her to stay with the MC precisely so they can gain a powerful ally. Lyriel is another case, maybe there is a way to help her and her family get her kingdom back or whatever it was. But at this point I'm just fantasizing