The smile on her face was probably disconcerting, probably because this was not the moment when she should have been smiling. He was confessing to have issues with their relationship, so they were not really good. But it was, because at least he was talking about his issues with her, rather than having some throwdown with her months after the fact.
"C'mere you," she actually reached up and took a hold of his shirt. "You want something to change? Then do change it." That was basically giving him a free shot if he wanted to take it.