Reports have surfaced that Rob Kardashian dumped Rita Ora after she hooked up with Jonah Hill.

The stars recently ended their relationship, with reality TV star Rob claiming the singer had been promiscuous. Rob posted a series of angry tweets about Rita, alleging that she had been seeing other people behind his back.

Us Weekly is now reporting that Rob ended the short romance because Rita betrayed him with funnyman Jonah.

The publication alleges that Rita and Jonah met in a New York club and hit it off instantly.

"Rita spent the night with Jonah during a trip to New York,” a source revealed. “Then Jonah bragged about it to friends, Rob found out and Rita confessed! That was the last straw.”

Rob went public with his anger at Rita, unleashing a barrage of vicious comments about the beauty. The 25-year-old even claimed he had got Rita pregnant during the time they were together.

He also repeated several times that Rita had cheated on him and how shocked he was at her supposed infidelity.

"So you let me get you pregnant and you let others hit raw?" Rob fumed in one post.

"She cheated on me with nearly 20 dudes while we were together... But I mean 20?!!!! (sic)” another read.

Rita has remained silent about Rob’s allegations, with insiders claiming she was “really upset” following his heated Twitter outburst.

The singer cancelled a concert in Philadelphia on Thursday night because she is apparently battling poor health.

The show was originally scheduled for October, but re-scheduled to last night following superstorm Sandy.

Rita took to her Twitter account yesterday to reveal she was postponing once again. She didn’t give a reason for the cancellation, but a ticket website blamed the decision on “illness”.

"I am so sorry Philly for cancelling tonight. I will be back next year..and make it up to (you) I promise I love you! (sic)"