Here's some self-training to try: When you think of him, do not think of him by his name, but rather substitute 'Sir'. If you would think "Gosh, I wonder if 'John' would like this dress" instead think "Gosh, I wonder if Sir would like this dress." Do this everytime you think about him and hopefully his name will be replaced in your mind with Sir. It's a way of 'forgetting' his name.