I think it means that a person was hurt emotionally by someone that they care dearly about, and just when they think that they are going to be happy again, that very same person hurts them again, because they want someone to be more miserable than they. And they finally see that they are hurting him/her yet they can't leave them behind and they want to help them get happier. So when the person tries to bring them down again, they help them and show them that they can help him with his problem to be happier.