I could be completely wrong here, heaven knows it wouldn't be the first time, but it seems as though the song is about someone who wonders how their boyfriend/girlfriend lives so happily and so freely when they're feeling so much pain. The line "Your lightness darkens me" kind of made me think that. It seems like the singer sees it as unfair that the other is so happy and so unaffected, that it simply makes her feel even worse.
I could be completely wrong here, heaven knows it wouldn't be the first time, but it seems as though the song is about someone who wonders how their boyfriend/girlfriend lives so happily and so freely when they're feeling so much pain. The line "Your lightness darkens me" kind of made me think that. It seems like the singer sees it as unfair that the other is so happy and so unaffected, that it simply makes her feel even worse.