According to the insider, Queenslander Ken leaves his TV bride Tamara for MAFS meltdown queen Jessika Power.
The caller, who is close to Tamara's best friend, said he was told Dan slept with Jess.
Fitzy & Wippa grilled the source and asked if he was referring to a comment made by blonde bombshell Jessika in a MAFS promo clip, where she calls new entrant Daniel "not a snack - more of a meal".
"Mate, I know it's a fact - it's actually going to play out on the show," Ken revealed.
Asked if Tamara was "shattered by the experience", he jokingly told the show: "Well I haven't got that far into it, because I'm a bloke."
The revelation will no doubt come as a surprise to MAFS enthusiasts, who watched sparks fly between Daniel and Tamara as she walked down the aisle.
Daniel gasped "she's beautiful!" and Tamara was equally impressed, declaring "he's tall, muscly, [got a] strong jawline - I couldn't ask for anything more".
"I am super impressed, there’s definitely a sexual attraction there," Tamara admitted.
"I’ve strong feelings towards her, I’d be lying if I said I didn't want a bit of hanky panky..." Daniel told the cameras.