[Considering who she was raised by, it's no surprise that she has the same expressions. It hurts to hear him say it even though she already suspected. Maybe even more so than to toss aside her feelings for him.
He'd been a father to her when her own couldn't be around. Zero had never been a story to her, not a figure trapped in ice that she only knew based on the feelings of those in her life. Growing up he'd taught her many things, helped her with her schoolwork when her mother floundered, put her on the stool so she could reach the counter when Ai wanted to learn how to cook beside him, carried her on his shoulders when she'd been perfectly capable of walking.
But he doesn't remember any of that. He doesn't remember her. He doesn't even know who she is.]
My name is Ai. She's my mother.
[Ai says nothing of her father. And maybe it's because she feels as if she not only gave up her crush on him but it's also partially because it feels as if she just lost a parent.]