Wasted Time

When we're in relationships that fail, and the grief of that failure is still fresh, it's easy to view the time you spent with that person as "wasted", because the relationship ended. You devoted time getting to know someone and sharing yourself with them, and it seems that it's all for naught, because that person no longer desires your company in that capacity. The girl in the song has experienced many such failures, and has become disheartened by them - she's wasted so much time on relationships that she feels weren't worth the investment since they failed her, and she's weary at the prospect of wasting any more.

However, the point the singer is trying to express is that even though the outcome of these relationships wasn't successful, that doesn't mean the time was wasted, as hard as it may be for the girl to accept in her current emotional state. If you never experience failure, you never learn how to succeed. Although it's unfortunate, sometimes success comes at this price. As Marilyn Monroe once said, "good things fall apart so better things can come together".

And by the line "to keep it together, we got to leave it alone", he means that we can't try too hard in our pursuits - to achieve that success we desire that always seems like it's taking too long in coming, sometimes we have to stop trying. The dichotomy of "together" and "alone" also express that the relationships, although they represented the togetherness the girl desires, weren't the right ones. In order to finally find the person she wants to be with, she must be by herself for a while longer.

Very poignant.