The Ultimatum
During the remainder of that season, Joe would pop in and out of Rhoda's life, but they never reconciled and in the episode "The Ultimatum", Rhoda finally issues Joe an ultimatum: either he can really try to make their marriage work, or she's going to start seeing other people. He tells her to see other people and exits the series. By the beginning of the fourth season, it was announced that their divorce was finalized.