How do you help a hurt child when their name is forgotten?

We have 3 children. My husband forgets our middle child's name. Why this one I don't know. Rationally I know he can't help it but it hurts her so bad. She has probably spent more time helping him than the other 2. She has 2 children that he calls the little boy and the little girl. They are 11 and 13. We have a dog that he loves to death and occassionally he forgets his name but when he forgets our daughter's name it really upsets her. He knows she is his daughter and he knows who she is, he just can't call her name. I made cards on advice of a speech therapist for him to look at everyday with all the family names on it. Wonder why his mind works this way and what can I say to this child? I know this is so trivial to some of our problems but it hurts me to see her hurt. She knows he can't help it. But she will say Daddy why can't you remember my name?