Given the question: Found the following article online, use it to answer the question: Why did Clark's mother stop in Chicago?  Returning from a Hong Kong business trip, Beth Emhoff has a layover in Chicago to rendezvous with a former lover before returning to her family in Minneapolis. She appears to have contracted a cold during her trip. Her six-year-old son from a previous marriage, Clark, also becomes sick and is sent home from school. Beth's condition worsens and two days later she collapses with severe seizures. Her husband, Mitch, rushes her to the hospital, but she dies of an unknown cause. Mitch returns home and finds that Clark has also died from a similar infection. Mitch is placed in isolation, but seems to be immune to the disease. He is released and returns home to his teenage daughter Jory, though they are unsure if she's inherited his immunity. She decides to stay with her father regardless. Mitch struggles with learning his wife was unfaithful, and protecting his daughter from infection. Meanwhile, everyone who had contact with Emhoff begins to spread the disease around the world. In Atlanta, representatives of the Department of Homeland Security meet with Dr. Ellis Cheever of the CDC and fear that the disease is a bio weapon terror attack over the Thanksgiving weekend. Dr. Cheever dispatches Dr. Erin Mears, an Epidemic Intelligence Service officer, to Minneapolis to begin investigating. Mears traces the outbreak to Emhoff, but after setting up triage camps in large venues, Dr. Mears becomes infected. Her evacuation is postponed, as airports close ahead of a quarantine. She later dies and is buried in a mass grave. As more and more people become infected with no cure in sight, social order begins to decay, with rampant looting of stores and homes. The U.S. President is moved underground while emergency services suffer absenteeism and no longer respond. Mitch and Jory attempt to escape to Wisconsin, but the borders are closed.
The answer is:
to rendezvous with a former lover