What does this song mean?

[BabyPiglet]

I was listening to Black Horse and the Cherry Tree by KT Tunstall earlier and I realized something. I have absolutely no clue what this song it about. It makes no sense! This is really bothering me now, and I won't let it go until I find out. Lol.

http://www.youtube.com/watch?v=HYEU91d8ngc

Lyrics

http://www.metrolyrics.com/big-black-horse-and-a-cherry-tree-lyrics-kt-tunstall.html

 

[PurpleDucky]

http://www.songmeanings.net/songs/view/3530822107858539236/