It could be possible that Midori still has feelings for Maki too, though I don't really know about that.
I've met people who only got into a relationship because the other(A) was emotionally damaged from a certain event and needs the other(B) to be their emotional support. The reltionship didn't really last long since B started questioning whether what A feels for them is really love or just distraction in a way(?) though A was pretty much emotionally okay now at that point and came to an understanding with B even as they separated.