They weren’t gossiping in that pineapple under the sea.
“SpongeBob SquarePants: The Broadway Musical” star Lilli Cooper admitted she had no idea her co-star Ethan Slater was dating Ariana Grande until the news broke.
“I was surprised,” she told Page Six exclusively at the opening of “The Cottage” Monday night.
Cooper, 33, played Sandy Cheeks opposite Slater’s SpongeBob during the musical’s Chicago and New York productions in 2016 and 2017, respectively.
“I haven’t spoken to him in a while,” she confessed to us, noting, “It’s an interesting coupling, for sure, unexpected.”
Page Six confirmed last week that the “Thank U, Next” singer had split from her husband of two years, Dalton Gomez, and moved on with Slater.
The new couple met while shooting the upcoming film adaptation of “Wicked,” in which Grande, 30, plays Glinda the Good Witch and Slater, 31, takes on the role of Boq, a Munchkin who becomes the Tin Man.
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Slater is still legally married to his high school sweetheart, Lilly Jay, and they welcomed a baby boy just last year.
A source recently told Page Six exclusively that Jay is a “wreck” and was “completely blindsided” by her husband’s new romance.
Cooper, for her part, is staying away from her former castmate’s headline-making drama and instead focusing on her latest play, “The Cottage,” which also features Laura Bell Bundy and Eric McCormack and is directed by Jason Alexander.
“I was pinching myself. I couldn’t believe it. It was so surreal,” she told Page Six of her casting. “I watched [McCormack in] ‘Will & Grace,’ for sure. I didn’t watch much of [Alexander in] ‘Seinfeld,’ but what I did watch was Rodgers and Hammerstein’s ‘Cinderella’ with Brandy and Whitney Houston, so that’s what I really know Jason from.”
Cooper — who originated the role of Martha Bessell in “Spring Awakening” alongside Lea Michele and Jonathan Groff — described herself as a “total Broadway geek.”
“I grew up backstage on Broadway. My dad’s an actor [Tony winner Chuck Cooper], and this is my sixth Broadway show. I’ve been a big Broadway musical fan since I was born,” she shared.
Celebs who came to cheer on the cast included Bryan Cranston, McCormack’s “Will & Grace” co-star Sean Hayes and Steven Weber. Vanessa Williams and Lea DeLaria, who starred opposite Cooper in the Broadway show “POTUS,” also attended.