My husband and I enjoy entertaining friends and neighbors with dinners, cocktail parties, and other festive events throughout the year. We are friends with one couple we include frequently. They are bright, enjoyable people, but they don’t know when to leave. We had one cocktail party scheduled from 5 p.m. to 8 p.m. Most people left by 8:30, a few stragglers stayed until 9:30, and this couple finally decided they should head home at midnight. They always stay at least a couple of hours after all the other guests have gone. Is it ever appropriate to send guests home? If so, how do I do it? The wife has very strongly held opinions about etiquette—and heaven help anyone who violates her rules!
—Pulling in the Welcome Mat
Re: Just ask them to leave
So many phrases to choose from that politely convey the party is over and it's time to start wrapping things up. The OP needs to choose one.