Hmmm. I think "what" converted her was more important than the fact that her "understanding" was what he wished for. For the story to hold up, and for the meaning to be maintined, she would have to truly change because of the humanity with her. I think his "storm", his falling and uglyness, brought her to change. If supernatural influence is being exercised here, it is in creating the circumstance to bring out his storm, rather than waving a wand over her, to create the change. Her change came about because of the change in Harry......rather than because ( at least directly ) he wished it and it was done for him. Otherwise, his excellent humanity is cheapened and shown to be rather insignificant. Now, were forces woking to make Harry rage direct or indirect.......they seem indirect. We accept as a premise that they exist. But, they rely on Harry, and Harry has a choice. Remember the old man pleading with Harry not to change. He knows Harry is capable of change. This capacity to change is the crux...and fortunately when he does change he gets what he needs, his wife's understaning. With the understanding, the stregnth to go on. If this were to be artificialy created, then I think the story suffers. For it diminishes Harry, and all of us, as people with choices.