MARRIED At First Sight’s explosive love triangle is in for a twist that no one saw coming.

In a dramatic new teaser, it’s looking likely that unfaithful husband Dean Wells is preparing to doublecross Davina Rankin, the contestant with whom he’s been cheating on his bride with.

Last we checked in, Dean and Davina had finally acted on their saucy talk, sneaking off to a private corner of the group dinner party to secretly engage in some heavy petting.

During their little session, they both agreed to leave their respective partners during this Sunday’s commitment ceremony.

But it appears there may be a major last-minute switch.

In the new promo for Sunday night’s episode, it’s apparent that Dean left the dinner party — and his tryst with Davina — and went home to get jiggy with his wife, Tracey.

The pair are seen waking up together in a rumpled bed, with Dean telling the camera in private: “There is that fire in the belly with Davina ... but after the dinner party ... Tracey and I had fun, and it was intense.”

Later, he seems to be grappling with his impending decision.

“I’ve got Tracey here, I’ve got Davina here — either way, I’m going to be the bad guy.”

Davina has every right to be suspicious of his intentions, too — it seems he’s also been lifting his game with Tracey outside the bedroom.

“Me and Dean are doing really good, actually. I feel like I’ve got nothing to worry about, I’m feeling much better,” Tracey tells the camera.

The narrator then reveals that of the three members of this messy love triangle, “one of them is about to get hit by a bus ... and it’s not who you think,” while fellow contestant Nasser can be heard shouting angrily: “He’s played you, and he’s played her!”