This plot had been teased and - with Robert's track record - it was hardly a surprise to anyone, but actually seeing him cheat on poor Aaron was too much for some viewers.
The Lothario called on Rebecca in last night's episode after a disastrous visit to see his husband in prison.
Robert could see that Aaron was taking drugs - and furious that he appeared to have no interest in what was going on in the outside world, particularly with his troubled sister Liv.
Back in the village and fuelled with whiskey and self-pity, the chancer messaged the one person in the village who is always at his Bec and call. (See what we did there?)
His posh totty ex Rebecca naturally came running and listened as Robert poured his heart out, declaring that he and Aaron were finished.
When he then moved in for a kiss, initially the blonde beauty pulled away.
But as Robert told her that he and Aaron had never been the same since she came back to the village, she began to melt.
As Robert whispered that he loved her, Rebecca eventually succumbed.
Just to add insult to injury, the pair slept together in the marital bed of Robert and Aaron's new home.
Viewers - notoriously protective of Robron's relationship - hit the roof.
One posted to Twitter: "I am disgusted by Emmerdale I just say this, and Rebecca is the most disgusting of all."
"Sorry @emmerdale - it's been a blast but this is 1 twist too far. Any number of other ways to tell this story, and this is the worst choice."
"Wow. IT'S GONNA TAKE SO MUCH FOR @emmerdale TO REDEEM THEMSELVES. I WAS FIGHTING THEIR CORNER. THANKS A BUNCH!"
One simply wrote: "#byebye #emmerdale"