The person who leaves early may have enjoyed the evening enough to want another one.

Leaving early is usually read as a verdict, and it rarely is one. People have trains, sleep, children, medication, an early start, a limit on how long they can be in a crowd. A departure carries information about the shape of someone’s day rather than about how the evening went, and the person going often wishes they could stay.

When someone leaves before the end, say you are glad they came and mean it. Skip the joke about it. If you are the one going, give the reason briefly and ask for the next date on your way out.