Oz’s love spell is cast wide

WHAT happens in Vegas doesn’t need to stay in Vegas, in Ariana Grande’s case.

The pop star’s affection for her “Wicked” costar and off-screen squeeze Ethan Slater — who plays a Munchkin in the movie musical — was on full display at a party in Las Vegas after they premiered scenes from their upcoming film Wednesday.

Co-leads Grande and Cynthia Erivo presented the clips at CinemaCon, where Hollywood studios show off upcoming blockbusters to movie theater owners to whip up interest.

But industry sources told us they were gobsmacked to see Slater joining Grande in the spotlight at an after-party at Nobu.

The duo “completely blindsided” his wife, Lilly Jay, when they started dating over the summer while shooting the movie. A source described the situation as “horrible” at the time, telling Page Six, “They were high school sweethearts. They have a baby! She’s a wreck.”

Production sources also told us Jay visited Slater on the set with their baby, and Grande spent time with them. They reportedly even went on double dates with Grande and her then-husband, Dalton Gomez.

We’re told the couple was flaunting their love at Nobu, as Slater “was leading her through the party by the hand. He was taking the lead,” a source told Page Six.

Our source described Grande and Slater as “very sweet” — and emphasized they were “very cuddly” throughout the evening.

We figure Grande took her own hit “Yes, And?” to heart, which includes such lyrics as “Now I’m so done with caring / What you think / No, I won’t hide.”

The studio didn’t seem to be bothered, either, by the couple’s controversial off-screen relationship, according to sources at the party.

“I thought they’d downplay [their relationship] for promotion. [Universal] doesn’t seem worried,” the source said.

The “Wicked” actors are reportedly shacking up together, happily ever after, in NYC.