The unsubstantiated allegations were contained in a series of bitter tweets from Rob Kardashian, which were quickly deleted.
Rob Kardashian said he was “disgusted” with Rita Ora.
“She cheated on me with nearly 20 dudes while we were together… But I mean 20?!!!!” he tweeted in the early hours of Monday morning.
Minutes later Rob Kardashian continued with his tirade against the star, writing: “How can a woman who is so busy trying to start her own career have time to be with so many dudes while in a relationship?!”
And he added: “I am actually disgusted.”
The tweets were live for around 30 minutes before Rob Kardashian had second thoughts and deleted them – but not before they went viral.
Having removed the tweets Rob Kardashian went silent on the matter for several hours, instead promoting his designer sock range.
He then returned with renewed vigor, tweeting a series of vitriolic remarks criticizing Rita Ora’s “loyalty” and self-respect and calling her “sloppy”.
“Respect thyself” he wrote, referring to himself as “a Faithful man”.
“When a woman cheats on you with one man I can live with that,” he claimed. “People make mistakes, trust me. I have forgiven numerous times…”
It appeared Rob Kardashian’s sister Khloe was not happy with her little brother, tweeting: “Rob be nice kiddddd.”
And she later reflected: “Social media is so much drama. Hehehe thank goodness there was no social media when I was younger. Too much drama in the LBC.”
Rob Kardashian, 25, was due to celebrate Rita Ora’s 22nd birthday at DSTRKT nightclub in London last week, but never appeared.
Rita Ora had reportedly called things off with the Keeping Up With The Kardashians star due to her hectic work schedule and their incompatible jet-setting lifestyles.
A source told The Sun: “It’s really sad – they really liked each other but with him living in LA and her over in London, it was becoming impossible to maintain a relationship.
“They’d only decided to go public with the romance a couple of months ago so as not to put any pressure on themselves but they’ve already split.
“Rob has now deleted everything on Twitter that reminds him of Rita.”
After first being spotted together back in May the couple denied they were dating for months, until going public at the end of October.
Rob Kardashian appeared to confirm the news by tweeting a picture of them kissing and writing: “Me and my baby.”
While the reality star’s family had welcomed Kim Kardashian’s new boyfriend Kanye West into their clan, she never appeared to warm to Rob’s girlfriend and caused controversy in August when she declared he needed to find an Armenian girlfriend instead.
Kim Kardashian tweeted: “When out to dinner w my brother @RobKardashian every gorgeous person Persian/Armenian girl stares at Rob! I think that’s what he needs in his life!”
Rob Kardashian has failed to emulate the huge success of his three Kardashian sisters despite appearing on Dancing With The Stars.
He has been seen on the family reality show complaining about his lack of success or money.
Rob Kardashian currently has his own designer sock line.
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