Ep 21. My Part-Time Wife

Rob Petrie (Dick Van Dyke), an aspiring comedy writer in New York, juggles the demands of his job, his happy home life with his wife, Laura (Mary Tyler Moore), and his wacky co-workers. In season three episode 21, titled "My Part-Time Wife," the Petries face a crisis when Rob's new secretary, Sally (Rose Marie), accidentally leaves her purse behind, revealing that she is married. Rob feels betrayed by Sally's lie, but when he confronts her, she explains that she and her husband live separate lives and only see each other once a year. She begs Rob not to tell anyone, and he reluctantly agrees.

Meanwhile, Laura is excited to have her friend Millie (Ann Morgan Guilbert) over for a dinner party, but she has to cancel when she realizes that Rob will be working late on a project with Sally. Millie suggests that Laura invite her over anyway, and the two women have a great time gossiping and catching up. However, when Millie accidentally discovers Sally's secret, she can't help but blab to Laura.

The news of Sally's "part-time marriage" spreads quickly among Rob's co-workers, and soon the whole office is buzzing. Rob feels guilty for betraying Sally's confidence, but Laura is upset that he kept such a big secret from her. She worries that their own happy marriage might not be as strong as they thought if even someone like Sally couldn't make it work.

As the tension mounts, Rob tries to smooth things over with Sally, but she tells him that he has to come clean with everyone about what he knows. At first, Rob balks at the idea, but eventually he realizes that it's the only way to make things right. In a final confrontation, he confesses to his boss, Buddy (Morey Amsterdam), and their co-workers that Sally is married, but that she has a good reason for keeping it a secret. To Rob's surprise, everyone is understanding and sympathetic, and they all agree to keep Sally's secret safe.

In the end, Rob and Laura make up, and they reaffirm their love for each other. They realize that they don't need to live separate lives like Sally and her husband to maintain a strong marriage. They can work together to overcome any obstacle and stay committed to each other for life. The episode ends with Rob and Laura sharing a sweet moment together, as always.