At the end of chapter seventeen, Kathy decides to leave the cottages. What betrayal, by Ruth, leads her to make this decision?

Things come to a head when Ruth, Tommy, and Kathy are alone. Ruth ridicules Tommy over his drawings in front of Kathy, and then she claims that Kathy supports her. She intentionally drives a wedge between Kathy and Tommy, as she later admits to doing so. Ruth goes even further, when in the guise of a friend, she offers Kathy advice, telling her that Tommy does not like women who have been promiscuous. Not long afterward, Kathy decides to start her training as a carer and to leave the cottages.