I don't think it necessarily has to be about a guy or be a love song, it could just as easily be a best friend, who has to say goodbye but knows that her friend will still always be in her heart. It could also be about death but I think it sounds more like they're just far apart, because of the line that says "they get lost in the tears of this goodbye," it sounds like their final good bye is one where her friend is awake and alert when saying good bye.
I don't think it necessarily has to be about a guy or be a love song, it could just as easily be a best friend, who has to say goodbye but knows that her friend will still always be in her heart. It could also be about death but I think it sounds more like they're just far apart, because of the line that says "they get lost in the tears of this goodbye," it sounds like their final good bye is one where her friend is awake and alert when saying good bye.