The thing is? Even if Midori has been awful to Maki since their reunion (YMMV, of course), she can be awful for sympathetic reasons.
I feel like she'd been reaching out for some happiness but then slapped her own hand back each time because she's caught up in the idea that she's not "allowed" it - because she has her child's father, because it's not okay for a woman to be with a woman. Those kinds of ideas that actually trap people in abusive relationships and in the closet, or in a whole range of other bad situations. When someone's messed up over something like that, it can make them send mixed messages and be really difficult to be with even just for normal friends, never mind someone they love but feel like they can't have. It's a horrible, self-reinforcing trap to be caught in.
I seriously doubt that Midori is acting like this toward Maki because she takes any joy out of messing with her.