She can't possibly know what the way she eats her yogurt does to him.
It makes him uncomfortable (among other things), not so much because of the way her lips slide over the plastic spoon, but because of the way he knows he's watching her.
He's tried concentrating on his sandwich, on the mess on the table, on the yogurt container itself—Mixed Berry. But his gaze always manages to work its way back to her face and that lucky, lucky plastic spoon.
He feels that he shouldn't be watching her like that, that he's not allowed to be watching her like that. That, most importantly, she wouldn't want him to look at her like that.
He thinks about standing up, leaving the kitchen, but, honestly, where would he go? She'd just follow him, ask him what's wrong. What would he say?
So he stays, because her company and his thoughts are better than being left with his thoughts alone.
She catches his eye across the table, smiles around that spoon, and he thinks about telling her.