Why does the man leave early?

M: I’m afraid I must be going now.
W: Must you? It’s still early.
M: I’m afraid I really must. I have to meet a midnight plane.
W: In that case, we can’ t keep you.
M: Well, thank you very much for a pleasant evening.
W: Thank you for coming. You must come again.
M: Thank you. I will. Good-bye.
W: Good-bye. I wish you a very good journey home.