Season 4: Episode 97: Robert's Divorce
While out for a family dinner, the Barones spot Robert's ex-wife, which prompts them to reminisce about the demise of his marriage. The family tells Amy the truth about Robert's failed marriage to Joanne, whom Frank not-so-affectionately refers to as "a nutcracker." The surprise sighting also brings back some personally harrowing memories for Robert--although, when Joanne suggests the ex-spouses get together, Robert seems interested.