Fans of the show know Robert was leading a double life being engaged to both Michelle and Vicky.
But when Michelle found out about Vicky's pregnancy, she confronted the chef and he told her that he had a one-night-stand with Vicky whilst they had split up.
Michelle later confronted Vicky who told her the truth - Robert had also proposed to her.
The businesswoman later returned home and told Robert that she believed his side of the story, but she was actually plotting revenge.
After getting the chef to sign the Bistro over to her, Michelle outed her cheating fiancé on their wedding day in front of their friends and family.
Meanwhile, the night before the wedding, Vicky went missing after an altercation with Robert.
After the wedding drama, Vicky's son Tyler turned up at the church wanting to know where his mum is.
I can imagine maybe Robert gagging Vicky and holding her hostage somewhere, pregnant or not.
The teenager also claimed the house had been scrubbed with bleach, making Robert look suspicious.
Although there is a popular theory that Vicky and Michelle were working together to fleece Robert, viewers have another theory that Robert kidnapped Vicky and is holding her hostage.
In a Digital Spy forum called 'Michelle is in cahoots with the mistress' one viewer said: "I don't think Robert has murdered Vicky (it would surely be too obvious). Just bound and gagged her somewhere in my opinion."
Another said: "This is all very true, I thought this yesterday, I can imagine maybe Robert gagging Vicky and holding her hostage somewhere, pregnant or not.
"Considering he brought his van to her house maybe Michelle got Vicky to rig cameras in her house to see how threatening Robert could be.
"Considering what Carla said to her on the day of Sinead's funeral 'be careful, Robert can be a nasty piece of work when he's angry' or something along those lines.
"I know it's unlikely that Vicky would put her unborn child in danger but it wouldn't surprise me to be honest, considering the very odd stories this show pumps out."
Another viewer added: "I don't see this joint revenge thing at all to be honest.
"I don't think Michelle is the type to be able to bring herself to join up with someone she considers so far beneath her. Could be wrong of course."
Coronation Street airs on Mondays, Wednesdays and Fridays at 7.30pm and 8.30pm on ITV.
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