I wouldn't say we feel happy. But, forgiving lightens our hearts. The problem I think most folks have with forgiving is that they think it lets someone off for the harm they caused. But, forgiveness doesn't release someone from consequences. They took a piece of your power to hurt you. But, holding on to the hurt caused by such a person, gives more of your power to them to let them keep hurting you over something you already survived. Forgiving them, breaks that hold and returns your power to you.