I would say this is a little bit about a broken relationship w/ a girl, but I think it's more of how he lost his way w/ God due to the girl. I think he's saying that when we turn away from God, we can't accomplish anything ("I missed what I was supposed to learn"). the only lesson we can learn away from God is that we need Him ("all I learned about was missing you").
it's aaron, not erin. (he's a boy).
I would say this is a little bit about a broken relationship w/ a girl, but I think it's more of how he lost his way w/ God due to the girl. I think he's saying that when we turn away from God, we can't accomplish anything ("I missed what I was supposed to learn"). the only lesson we can learn away from God is that we need Him ("all I learned about was missing you").