Casey Wilson, Ken Marino Casey Wilson, Ken Marino

If you call Marry Me, NBC's new sitcom, Happy Endings: The Year of Penny, Casey Wilson isn't going to stop you.

"It's flattering. I loved doing the show and I'm so happy that people who watched Happy Endings loved it so much," Wilson tells TVGuide.com. "There weren't a lot of them!"

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On Marry Me (premieres Tuesday, 9/8c), Wilson plays Annie, who unknowingly ruins her longtime boyfriend Jake's (Ken Marino) proposal by going on a hysterical tirade while he's on bended knee — not to mention with friends and family hiding in the apartment. Like Happy Endings' Penny, Annie is a sweet, emotional, flustered spaz. Like Happy Endings, Marry Me was created by Wilson's husband David Caspe and traffics in fast-talking, pop-culture-heavy zingers. And like Happy Endings, Marry Me will feature Derrick (Stephen Guarino), who will bring the draaama in the Halloween episode. "He knows both groups," Wilson says.

But that's where she believes the similarities end. "I think the shows are fairly different," she says. "I think they have the same sense of humor for sure and the same kind of rapid-fire jokes, but I think there's a lot more heart to Marry Me and it's a lot more grounded. We get to go a little deeper here. We could get away with so many different, crazy things on Happy Endings, but we can't do that here. And I think the ensemble is not all terrible people like on Happy Endings!"

Though Marry Me's whole premise rests on Jake and Annie's engagement, Wilson says the series is more about the ensemble. That includes Gil (John Gemberling), Jake's divorced pal; Dennah (Sarah Wright), Annie's single BFF; Kay (Tymberlee Hill), Jake and Annie's neighbor; and Annie's two dads, The Kevins, played by Tim Meadows, 53, and a grayed-out Dan Bucatinsky, 49, whom Wilson, who turns 34 on Oct. 24, jokes are "basically my peers than dads."

Happy Endings eventually abandoned its initial premise — Alex and Dave's breakup complicates friendship dynamics — after the first season to become a full-blown, absurd group-com, but Wilson says this has always been Marry Me's plan. "The show at the core is about Ken and my relationship, but it was never going to be just about this one relationship," she says. "There just wasn't enough real estate in the pilot, but the ensemble is in every episode and we've got a lot of fun with them. Tymberlee is an old friend of mine in real life and John is just unparalleled. ... The genesis of the show was this engagement gone wrong and from there, it morphed into this great ensemble. It's kind of taken on a life of its own."

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The same can be said for the story lines. Marry Me is loosely based on Wilson and Caspe's relationship — he even told network executives that he was planning to propose as part of his pitch — except for the whole botched engagement thing. "We had a very smooth engagement, very fun. Nothing disastrous," Wilson notes, adding that she's not too concerned about mining from her personal life for the show.

"Maybe I should be more worried!" she says with a laugh. "No, but it's a sitcom, so it's certainly not mining the darker aspects. And there are 14 writers and they're all bringing their own weird relationships to the table. We served as the jumping-off point for Jake and Annie, but from there on, it's anything. Ken himself is obsessed in a very sick and real way with karaoke and now Jake is obsessed with karaoke. There have been two [karaoke scenes] so far. We did 'Piano Man' in Spanish. You'll have to watch to find out why. It's a duet. My Spanish is fairly good."

The second episode will also be based on a true story — or at least feelings. Jake will move in with Annie, who starts to feel claustrophobic. "So I transition into my car and am half-living in my car," Wilson says. "That didn't happen [with Caspe], but I have felt that in past relationships where you're unpacking and so excited and as you unpack, you look around and are like, 'Oh, God. I'm with this person for a while.' You start to feel like, 'I don't want to be here!'

"The whole show is picking kernels," she continues. "I think everything that is funny is fair game. ... But I think if we took everything from our lives, people will be bored."

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In real life, Wilson and Caspe were engaged for a full TV season — September 2013 until they stole Kimye's thunder Memorial Day weekend — and it looks like that will be the case for Jake and Annie as well. "I think they're only going to be engaged through the first season. I think they'll get married pretty quickly," Wilson says. "The show is not about a will-they-won't-they. Spoiler alert — they are going to get married and we'll move on from there.

"And then," she deadpans, "they'll get divorced in Season 3. Season 5, they die. It's a twist!"

But after Jake and Annie tie the knot, will the show change its name? "I have no idea," Wilson says. "I don't know what they'll call it. It'll be like Don't Be Tardy for the Wedding became Don't Be Tardy. Maybe we'll become Married."

Marry Me premieres Tuesday at 9/8c on NBC.