The combination of how the song builds up slowly to a very emotional climax towards the end of the song and how it reflects on how I felt about someone (again, being something that I didn't tell that person about and doing it again later to someone else) is why the song has such an impact on me.

It is a song that I really like listening to when I'm about to fall asleep, since it starts out quite slow and mellow, and causes my depression to build up more and more, until I just pop.