Who is Ximena Ortiz from Memories of My Melancholy Whores and what is their importance?

Ximena Ortiz is the daughter of a family friend. One afternoon while visiting her family, the narrator accidentally walks in on Ximena taking a nap in the nude. He is subsequently so captivated by her beauty that he begins courting her. Over time, they become engaged. Unfortunately, once their passion burns out and they acutally have to talk to one another, they find they have nothing to talk about. On the day of their wedding, the narrator can't go through with it. He hides out in his house, ignores the knocks of Ximena's family members, and creates such a scandal that he nearly loses his job. Shortly before his ninety-first birthday, the narrator sees Ximena. She is old and confined to a wheelchair. He looks on her and grieves for the children who never were.