At least from my and my girlfriend's reading of the text, I wouldn't really describe their dynamic as the ways they're awful cancelling out, more like Millicent's encounter with Ember making both of them actually introspect and think for the first time in years. This is, of course, from Mill being absolutely horrific to Ember and it not reacting in a remotely reasonable or normal way, but that was the effect. The latter meeting being them both enjoying the fruits of their reflection and each other. I really appreciated this story about this type of relationship, even if it didn't end up as toxic as you wanted!