I think that this song is about seeing someone you had a relationship with. Maybe someone who ended the relationship for their own reasons, and left your feelings out. It is about seeing that person all over the place by themselves, available to the whole world accept for you, and yet they are by themselves, they are not receiving attention from anybody else, and it is a torture to you because you know how much you love them, and just how you feel about them. Yet there is nothing you can do but watch them wait or slip away, until somebody comes along and takes them from your life forever.
I think that this song is about seeing someone you had a relationship with. Maybe someone who ended the relationship for their own reasons, and left your feelings out. It is about seeing that person all over the place by themselves, available to the whole world accept for you, and yet they are by themselves, they are not receiving attention from anybody else, and it is a torture to you because you know how much you love them, and just how you feel about them. Yet there is nothing you can do but watch them wait or slip away, until somebody comes along and takes them from your life forever.