It's the certainty in his voice that makes it's mark on her, emboldening her. She can't help it. She just reaches out and takes his hand and pulls him towards her. There's always that risk with these moe types. Compliment them too much and they'll start acting like this.

Without thinking, she kisses him again, this time full on the lips. It's almost as though the writers are trying to tell her that she isn't really moe at all, but pretend-moe.