I should think the explanation is rather more direct.  Maggie doesn't
invite Seth to watch her operate or become fascinated with her, or
"stalk" her in the hall way.  For her, at the beginning, he is an
uninvited stranger.  Sung at the end, the song is kind of a return to
the beginning of the affair and Maggie's voice from the grave, as it
were.  Jesse Kalin

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