David and Jessica walked arm and arm to the gate. Every so often, Jessica took a sip from her coffee. David steered them around the crowd. As they passed a trashcan, he tipped the cup over and emptied it. That done, he put the top back on and pantomimed drinking it for a little while, then threw it in another can. He took out his ticket and held it in his hand, trying to think of a good way to get rid of Jessica without having to get on a flight to Chicago.

They stood at the ...