Perhaps reluctant to let their shared breakfast come to an end, both of them ate exceptionally slowly. Even after they finished, they didn't leave right away, dawdling and unwilling to go.
In reality, even though they had ordered a variety of dishes, they were just small snacks; most people wouldn't take this long to eat. Besides, with so many people waiting for a table outside, the proprietress finally got anxious and came over to offer them a twenty-percent discount, hoping they would leave soon.
