I think this song is about someone who has spent their life in and out of poor relationships, "giving themselves away" to people who don't care. It could either mean that they just sleep around, or that they are honestly trying to find someone to love but just choose losers. In any case, they've never really stepped back to see where their life is going, and now they are having a harsh wake up call - they're alone and obviously facing a major problem ("I don't know how to get you out of this one"). The chorus is interesting, because "heaven forbid" can go two ways: it can be sincere or sarcastic. He's either saying 'I hope you don't end up alone, you're such a nice person and it shouldn't happen to you' (sincere), or 'After the way you've lived, heaven forbid you should be alone without knowing why! ' (sarcastic).
But even though this person has got themselves into a bad situation, he's still telling them to "hold on tight" because it will turn out okay and they'll get through it. It's got very meaningful lyrics, like all of The Fray's songs. :)