Married At First Sight's Jonathan reveals exactly how he knows Emma, and we're shocked.

OK, you know how the brides and grooms who are COMPLETE STRANGERS and marry each other on NATIONAL TELEVISION are supposed to be the centre of attention on Channel 9’s dating show Married At First Sight?

That all changed when Emma – aka the worst wedding guest in the world – turned up mid-way through the first episode of the show’s fourth season last night.

READ MORE: The Twins Recap Married At First Sight, Episode 1

Emma wasn’t too happy about Jonathan marrying Cheryl. (And, look, to be honest, they are literally strangers so she kind of has a point.)

Emma even decided to tell the camera that Cheryl was not Jonathan's perfect match. Why?

Because "the perfect person for Jon is already out there."

Of course, many speculated that Emma was definitely, maybe the ex - or even the current - girlfriend of the 29-year-old entrepreneur.

So, what is the story with John and Emma? Arguably the most awkward wedding guest I've ever seen. #9Married

— Mark Foresi (@markforesi) January 30, 2017

The Crazy Ex Emma is EVERYTHING!! #9Married

— MatCHU (@mattOMFG) January 30, 2017

Emma for The Bachelorette 2017 #9Married

— Lendl Ryan (@lendlryan) January 30, 2017

I would have paid to be sitting next to Emma at that wedding...CrazyEx #9Married

— Joe Fitzpatrick (@JBAFitzpatrick) January 30, 2017

According to Jonathan himself, viewers weren't that far off the mark: Emma is the twin sister of one of Jonathan's ex-girlfriends.

"Emma is practically like a sister to me because she is the sister of one of my exes," he told TheFIX.

"They're twins. They're not identical. I think you have to have dated a twin to understand. People say they look similar, but they don't look anything alike."

It turns out that Emma's entire family - excluding her twin, who was once romantically linked to Jon - were in attendance at the MAFS wedding.

"They thought it was going to be hilarious for me," he said.

Yes...we can see how watching someone you know quite well marry someone who is a) a stranger and b) not related to you could be a fun family day out.

Listen to Clare Stephens and Laura Brodnik explain the best and worst moments of Married At First Sight on The Recap.

As for Emma's scene-stealing behaviour, Jon said he wasn't "really surprised" by her reaction to new wife Cheryl.

"She just is protective of anyone who's important to her. She's just always been like that," he said.

"She just laughed and was like, 'Did I make an idiot of myself?' And I was like, 'Yeah.' She's actually a lovely girl. She’s laughing about it now."