"
before?"
You turned to me, said, "No, I'll be
It saying that promises can be made to be forever but they do not last . It could also be a reference to a song by her ex boyfriend Alex day. The song is called "forever yours" and was written before Alex and Carrie were actually dating. It is more likely that she talking about how when you are in a relationship, you feel as if it is going to last forever no matter how complicated the circumstances may be but in actual fact this is never the case.