I guess this was always gonna be the big conflict here. Two kids who basically define themselves through taking care of someone else, who bonded almost exclusively over that image, were always gonna have issues reevaluating that relationship.
Guess we're gonna send the last few chapters making...
Yami at least has a reason to act the way she does, that girl has been through some tough stuff. Not really an excuse but I can empathize with the character.
But Yuu realy is just a blank-slate, no drive, no responsibility MC who somehow ended up in a story involving real emotions and people...