How does the author use foreshadowing in The Paris Wife: A Novel?

In Chapter Two, the reader learns from Hadley, who narrates the story, that she was vulnerable when she met the charming Ernest Hemingway. She was in mourning over the death of her mother and was looking for someone or something that would distract her and bring happiness into her life. The author foreshadows that a relationship may have existed between Ernest and Hadley's best friend, Kate, which could cause a conflict between the friends and a barrier to a relationship between Hadley and Ernest.