(ABC News) -- George Costanza wanted to end his relationship in the worst way.
"Seinfeld" actor Jason Alexander, who played the lovable loser Costanza during the show's nine-season run, explained the back story to one of the show's key moments during a Wednesday appearance on "The Howard Stern Show."
Alexander appeared on the show ahead of his turn in the Broadway comedy "Fish in the Dark," replacing Larry David, the co-creator of "Seinfeld."
The seventh season of "Seinfeld" features an arc involving George's engagement to Susan Ross (Heidi Swedberg). George is initially optimistic about the engagement, but later seeks to sabotage the relationship by taking up smoking, asking for a prenuptial agreement and pursing a coffee date with actress Marisa Tomei.
In the season's final episode, "The Invitations," Susan dies after licking poisonous, inexpensive envelopes for their upcoming wedding, a nod to Costanza's stinginess, and symbolizing the relationship's toxic impact on Susan's life.
According to Alexander, 55, the deadly finale was borne from the actors' troubles to connect.
"I love [Swedberg]. She's a terrific girl. I love her … I couldn't figure out how to play off of her," Alexander told Stern. "Her instincts for doing a scene, where the comedy was, and mine were always misfiring. And she would do something, and I would go, 'OK, I see what she's going to do, I'm going to adjust to her,' and then I'd adjust, and she'd change.
"I had done three episodes with her, and Larry calls me up at the beginning of the season and goes, 'Good news: I've got a great arc for you this season – you're gonna get engaged.' Oh, that's great! Who do I get engaged to? Susan. And I went, 'Oh, great. Who's playing George?' Because it was such a disaster," Alexander said.
Following filming, Alexander said, the core cast would go to dinner, and Alexander complained about his lack of chemistry with his on-screen fiancee. Initially, Alexander said, his fellow stars Julia Louie-Dreyfus and Jerry Seinfeld brushed aside his concerns. But after they started sharing scenes with Swedberg, they too acknowledged similar issues, and openly pondered the character's fate, Alexander said.
"Julia said, 'I know, don't you want to just kill her?' And Larry went, 'Kebang,'" Alexander said.
"Every time I tell this story, I cringe," Alexander admitted to Stern. "Heidi is the sweetest."
Following Swedberg's arc as Susan, she continued picking up acting roles, appearing in such shows as "ER," "Gilmore Girls" and "Bones." These days, the Hawaii native plays and teaches ukulele music and performs as the lead in the Sukey Jump Band.