Hi,

I don't think the song is about ways to leave, but rather about the idea that there must be fifty (plenty) ways to do so. As it happens, a few ways are mentioned, but if the chorus had been

"Fifty ways, fifty ways,
There must be fifty ways;
Fifty ways, fifty ways,
There must be fifty ways to leave your lover."

- the song would have been equally valid. (But that's probably not Paul Simon's way of writing choruses.)

OK, so the song isn't titled "The concept of the existence of multiple methods to end a relationship", but then, Paul Simon tends to write what comes to him naturally.

Bye,
                                                                Mysha