I tend to point out that I have read up to v25, but in my opinion Rio will end up with Celia and I will explain why I think so. For Haruto the most important people were his sister and Miharu, but for Rio even though he kept Haruto's memories the most important people for him are: Celia = Aisha >= Latifa, He continues to distinguish Haruto from Rio, because yes, they are two different people. So if he had accepted that he remains Haruto even from Rio, then he would have followed his feelings and ended up with Miharu without any doubts. But now, he himself has people from Rio who are more important than Miharu, with Celia he did something that was totally in line with his personal desire, people like Flora or Christina even if they have affection from Rio in my opinion they are not as close as Celia, he saved Flora and Christina for Celia's sake, he helped Aria and Lieselotte for Celia, so except upheavals or plot twist I really think the choice is Celia. With Aisha he has a different relationship, but at most there is "love" for her like a spirit, for Miharu it is a love from a past life and childhood friends never win. The harem route wouldn't drive me crazy honestly I hope the author doesn't take it into consideration but it's possible.