The overall theme of this song would be "You don't miss someone till they move on without you". She messed up a relationship she wished she hadn't. She cheated on him and then says she doesn't deserve it. She knows the relationship is over and he has moved on. But on the other end she hasn't and she just wants him for a little more so she can show him how she has changed and that she won't do it again. She may even be a little jealous of the new girl that has him now because she gets to hold him and she gives him all her love.