Her mouth opens to reply and then closes again, the protest dying before it's lived. She hadn't expected him to pick up on anything but he's surprised her, calling her out on something apparently quite obvious.

After a few moments of silence, she shrugs, visibly unsettled by the subject. "I feel guilty," she explains, "for having missed so much all this time. I've always tried hard to understand you, and now it turns out I never really stood a chance at it."

She feels guilty for it, and sad... and small.