Why does Nell continue to tail her mother's husband, even after being asked not to in the story, I Will Survive, from the collection, Table For Two?

When Peggy, Nell's mother, changes her mind and calls off the tail, Nell ignores her despite Jeremy's urging her not to pry beyond what has been asked of her, insisting that she has to know if John has done wrong by her mother and following him into the city anyway.