Married at First Sight preview shows Nicole leaving new husband Keller.

Married at First Sight‘s Nicole and Keller were meant to be the unlikely fairy tale couple of this season.

Keller, a heavily tattooed, 26-year-old former Navy worker won us over at his ‘wedding’, with his sense of humour and warmth towards his new bride and her family.

As we got to know him more he was dorky and charming and charismatic. We learnt his family has fostered children for 12 years, and he loves kids. He fell for Nicole instantly, and made their honeymoon in the Cook Islands look genuinely fun, dressing up in a coconut bikini and dancing in front of complete strangers. He was honest about the fact that no one drinks red wine for the taste. Who doesn’t want that?

But on Wednesday night, the fan favourite did something unexpected. At a dinner party with all the Married at First Sight couples, he snapped at Bella, who had shared that she and her experimental husband, Michael, had slept together after one night. She said she was open about sex, having had lots of relationships in the past.

"I bet you have," said Keller. "After sleeping with a guy after one night, I bet you've been in a lot of relationships."

That's where it started - and it ended with Keller trying to physically fight Michael.

It didn't take long for Nicole to challenge Keller, asking him why he would speak that way. She left the table.

And in the preview for next week's episode, things don't look promising for the couple. Nicole is clearly worried that Keller's dinner party behaviour wasn't a one-off.

"You don’t look very good, I don’t think it’s a good idea if you drink anymore," she says to Keller, who sits on the lounge looking miserable.

He retorts: "I'm a good boy... I know what I can do and what I can't do."

It's at this point that Nicole is shown packing her bags and leaving Keller.

In a later scene, Keller sits in a park and says, "I don't even know where she stayed last night, I haven't been able to get in contact with her."

"I just stuffed everything up."

Other scenes show Keller sleeping during the day, and Nicole sweeping up broken glass while telling the producers, "watch it all fall apart."

Nicole also says in a piece to camera, "it's embarrassing, I'm starting to see a little bit of a pattern."

After the dinner party, Keller posted a photo to Instagram apologising for his behaviour.

'Just want to say sorry if tonight anyone was offended that was not my intention so genuinely I apologise,' he wrote.

'I just stand up for what I believe in and defend the things I care about.'

It's unclear whether Keller's remorse for his actions will be enough for Nicole, but we'll know for sure on Wednesday, when the couple meet the experts to make their final decision.

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