NIMA-007 Grandfather lost his memory, thinking that his granddaughter is his wife.

Old age often leads to confusion, also known as dementia. The grandfather mistook his granddaughter for his wife, who looks beautiful and youthful. To avoid making him sad, she indulged him, even though it is unlikely for her to reach climax due to her weakened condition in old age. However, perhaps that is a misguided thought.