Kanna came back to take Mitsuki to success, instead she's finding herself falling into an old path.
Meanwhile, success is finding Mitsuki at home, while Mitsuki sees Kanna not as someone who would bring her to success, but rather a mother figure.
at least according to Joe, we hadn't heard that directly from Mitsuki, so we can put it off for now.
Mitsuki is on a good track, even without Kanna.
Joe is comfortable where he is, but he would be happy with Kanna by his side.
Kanna is… not. If she's running away, again, I think she's running away alone, again.
If she does, and Aya and Mitsuki haven't made up or come together at that point yet, it's going to trigger a major awakening in Aya*, because she can't deny the parallels between herself and Kanna with the past repeating.
(*also Joe)