Why do you think the author included the passage about the grave rubbing and the dead knight

This story serves as a connection between Susie, her mother, and her father. In the story, the woman cannot get over the death of her husband the knight. In Susie's story, her father cannot let go of her.... she's become the dead knight, and it was her mother's love for her father, who lay sick in the hospital, that needed to convince him it was time to move on.