I think this song is about two people's relationship and how it was just 'so close' to being everything and then someone or something just comes between them, and even though they know they are perfect for each other, they can't be together. I can totally relate to this song. Before my best friend and I had a falling out we were 'so close', and by the time it was too late, we realised that we both had feelings for each other, and we could've been so much more, and now we're 'so far' because we aren't even friends anymore. :(