Lydia Ramsey, author of Manners That Sell, has strategies on how to respectfully exit a conversation.
(1) “If you’ll excuse me, I’d like to go refresh my drink.” You can add, “Would you care to join me?” If he goes for the bar, you go for the hors d’oeuvre, and vice versa.
(2) Escape under the guise of being a good mingler: “It was just lovely speaking with you, and I’d so like to introduce you to … I’ll leave you two to talk.”
(3) Flattery: “I really enjoyed our conversation, but I don’t want to monopolize your time. I’m sure there are others who’d like to speak with you.”
(4) Excuse yourself from a conversation only after you’ve finished speaking—not after someone else finishes a story. You don’t want to leave him wondering what was wrong with what he just said.
(5) Make sure you actually leave the person’s side. You shouldn’t shift to the next group of people, or it will be obvious you just wanted out.
(6) And when more polite methods fail, there is always the old standby: the bathroom.