How, you may ask? Well, it's all to do with the colour of these finale two frocks.
Apparently, the theory dictates that whoever is wearing the lighter colour dress is the woman who will be crowned winner.
This year, however a spanner has been thrown into the works with both Irena and Bella wearing equally dark dresses (a ploy by producers to throw us off the scent?).
Bella is decked out in a stunning plum-hued Georgia Young Couture ensemble, while Irena wears a two-toned brown dress by Con Ilio.
With part of Irena’s dress made up of the lighter brown shade, this seemingly suggests she could have the edge over Bella, hinting she will win – but it will be close.
The fan theory has been doing the rounds for several years now and has held true in all seasons but one.
Last year, Chelsie wore a beautiful pale pink slip dress with light gold detailing on the bust, while Abbie is decked out in a sexy pewter halter-beck gown, meaning it was Chelsie who has captured astrophysicist Matt Agnew's heart.
While the Honey Badger picked no one and therefore ruled himself ineligible, fans were convinced Brittany Hockley had the upper hand over her love rival Sophie Tieman, thanks her white ensembles versus Sophie's cream-coloured outfit.
Given Irena and Bella are both wearing dark outfits much like Sophie and Brittany were both dressed in light outfits, this could be a huge hint that this year’s winner and their romance with Locky is doomed to fail.
In 2017, Laura Byrne won the heart of Matty J, but not before she stepped out in a white frock during the finale.
Unlucky-in-love Elise Stacey wore the darker shade of gold, and then went home broken-hearted.
The year prior was Richie Strahan's season and in the official final two promotional shot, Alex Nation hinted at her eventual victory by wearing a stunning light gold gown.
This was in stark contrast to runner-up Nikki Gogan who donned a vibrant red lace dress.
Proving that the theory does in fact have a leg to stand on was Sam Wood's season in 2015.
The women vying for his heart in the finale were Snezana Markoski (dressed in a beaded white dress) and Lana Jeavons-Fellows (wearing a slightly darker baby blue frock).
Again, it was the lighter hue and its wearer – aka Snez – who left the finale triumphant.
Even in Blake Garvey's controversial season, the "dress theory" proved correct as Sam Frost was proposed to while wearing a sparkling silver dress while runner-up Lisa Hyde was dumped in a plunging jet black gown.
The original Australian Bachelor, Tim Robards, also picked a winner that was predicted by an outfit.
Winner and Tim's now-wife Anna Heinrich wore a light-coloured beaded ensemble while rejected bachelorette Rochelle Emanuel-Smith left rose-less in a bright pink dress.
So, will the dress theory predict the future once again? We can't wait to find out!
