Juliet's mother (formerly Mrs. Carlson) was the mother of Juliet and Rachel. She and her husband informed their two daughters that they were getting a divorce, something that represented a traumatic event for both Rachel and Juliet. It was from her that Juliet heard the line she eventually quoted to Sawyer: that sometimes two people, even if they love each other, can't stay together. ("The Incident, Part 2")
The casting call described her as "Alice. Caucasian. Late 30s. Emotionally strong and tries to keep her feelings in check for her family. Unhappy in her marriage and tasked with telling her two young little girls that she and their father are divorcing."