How do the boy and the girl serve as a foil to the man and his former girlfriend in the short story, Why Don’t You Dance?

The young couple is a foil for the man and his former lover. Throughout the story, the man obsessively observes the boy and the girl's interactions. He seems enamored with the girl. The boy seems similar to the man, in that the majority of their movements mirror one another. The couple is a symbol of what the man had, and has now lost.