How does Walter end up reading Patty's autobiography? What is the result of this action?

Richard and Patty argue late one night while everyone is asleep, and when Richard returns to his room he finds Patty's autobiography on his pillow. After reading it, he decides to leave. Before he goes, he leaves Patty's autobiography on Walter's desk. Several days later, he finds Patty on his doorstep. Patty explains that Walter evicted her after reading her autobiography.