I don't know. When I hear the song and see the video, I see escaping from a society that is collapsing in on itself. I have a strange, macabre fascination with dystopian worlds, so maybe I'm predisposed to thinking that way, but the lyrics fit. Happiness hit her like a train on a track--for people who like that genre of literature (think Fahrenheit 451 by Ray Bradbury or Anthem by Ayn Rand), these societies always have a false illusion of happiness, so the happiness could be the realization of how false it is. And when the protagonist in these novels run away from the society, they have to leave behind everything they have, which usually isn't very much, but it means a lot. There are a few mistakes in the lyrics. One verse says "leave all your love and your longing behind" but another says "leave all your love and your loving behind." I believe it's longing.