MAFS' Gab has a theory to explain Nasser's surprising reaction to her decision to 'stay'.

When Married At First Sight’s Gabrielle Bartlett announced she was staying with ‘husband’ Nasser Sultan at last night’s commitment ceremony, the reaction from viewers across the country – and Nasser himself – was a surprise.

“He thought he was safe and that I’d leave,” Gabrielle told The Fix.

Gab explains why she chose to stay with Nasser:

But Nasser’s reaction was a shock, with Gab revealing she was expecting him to lose his temper. Instead, he seemed happy she made the decision to ‘stay’.

READ MORE: The Twins recap Married at First Sight: Gab just won this whole goddamn show.

“He ended up appearing to be quite positive,” Gabrielle told The Fix after Sunday night’s commitment ceremony.

“I was quite surprised. I thought he would be angry again. I thought he’d lose his temper again because I was so used to him going off like a terrier over the slightest thing.

“I thought, ‘Here I go. I’m going to drop the grenade’.”

The mother-of-one said she thinks Nasser's response was more tactical than genuine, and believes he is more worried about the reaction from viewers than he is about her.

"And I think at that point, Nasser flip flopped for what he thought the audience might like to hear. He felt that it was in his best interest to go with the flow right now and appear positive."

LISTEN: Gab is our feminist hero and we need to talk about it. Post continues after audio...

Tension has been high between the pair in recent weeks, and during homestays, Gabrielle accused Nasser of only being interested in her when the cameras were rolling.

She said she felt "isolated" and "alone", and Nasser, a 50-year-old fitness instructor from Sydney, didn't appear to do much to alleviate her concerns.

Sunday night's commitment ceremony was a chance for the couple to cut their losses, but Gabrielle wasn't giving up that easily.

"I wrote 'Stay' because I was wanting to operate by my set of standards, not Nasser's," she told The Fix.

"I made a commitment to myself that I would not leave until I felt I was completely finished, and I felt that I wasn't finished."

Listen to the full episode of our Married at First Sight recap podcast.