What is the relationship between the two speakers?

W: Excuse me, do you live in London?
M: Yes , I do. I live in Hampstead.
W: Hampstead ? I live in Hampstead, too. London is a funny place. I don’t know my next-door neighbor.
M: I live in Pond Street.
W: That’s funny! I live in Pond Street, too.
M: I live in number 24 Pond Street.
W: I live in number 23 ! You are my next-door neighbor !