The funny thing is, not having seen this video for several years, I always had it in my head as "the girl and the boy are both wandering around wistfully, thinking of each other and their former did-not-end-well relationship"-- as if it were a duet. Which, I guess, would be a creepy stalker duet, now that I'm considering the song in that light.*
It's funny how the videos can affect one's perception of the song and the lyrics (oddly, the other example that comes to mind immediately in terms of "and now I can never hear this song the same way again after seeing that..." is "Call Me Maybe"...).
*or, taking the song on it's own, no visuals, a creepy stalker monologue.