I have no idea what the actual relationship that inspired the song was like. I found it hilarious that the guy who broke her heart suggested that he should get credit/royalties for "inspiring" her album. At any rate after finding out that she wrote the song as a 20 year old (or something like that), it all started to make more sense to me.
I hear the song and I think of the 22 year old me who was feeling that way, and I wish I could tell her, don't fret. There is a partner, a husband, a life so much better than you could ever imagine waiting for you. Now all I need to find is the song that speaks to the "who knew life could be this good" feeling.