The Shadow keeps going on and on about killing her and wanting her to die. "Do it then." Prove to her that you aren't just posturing as terrible to lick your wounds, Goro."Because right now it just seems like you're lashing out at me to hide your pain."

Of course it did help that she knew her own Goro and she knew she was like that too. Just because she grew numb to it didn't mean that her Persona wasn't awakened out of pain that looks a hell of a lot like this Shadow's. She starts to think that he hasn't killed the other one not because he can't but rather that he won't. He probably is just as afraid of being alone as he is of being used.