its about one person's failure. It is considered symbolic of an ending relationship, however, it can also represent broken trust in a once long-lasting friendship.
I think it's about how a person doesn't really know what they've got till it's gone. In my opinion, it's about how a person is so caught up in other things, that he/she doesn't realize the value of another person. And even though they TRY, the damage has already been done and nothing can stop what has to happen in the end. It's about how time goes on no matter what. It's about how people don't realize the importance of something and watch the one thing that matters the most fly away, and they can't do anything to stop it in the end.