I did say I need to read it again, and even if Yuzu is not trying to "fix" Mei, by making her life better, which shouldn't be hard because her life sucks, Yuzu will end up fixing most of her problems in the process by giving her all the love and affection she needs, who needs therapy when you have the power of love?
The funny thing is that Yuzu has showed a significative character development, but this development has been forced by other people like Matsuri or Sara, Yuzu has been a secondary element.