Rita Ora is reportedly shocked her split from Calvin Harris has turned so "nasty".
The 23-year-old star began dating the Scottish DJ in May last year, but they called things off in June 2014.
Shortly before their breakup, Rita released track I Will Never Let You Down, which was written and produced by Calvin. Later she revealed he had blocked her from performing the song at the Teen Choice Awards.
"Rita is surprised it all got so nasty," a source explained to British magazine Star.
"She's on the verge of cracking the US and his choices could effectively hurt her career. But clearly Calvin had his reasons. There's a lot of unresolved anger between them."
Calvin, 30, has remained quiet about the relationship in the press, but he has used Twitter to express his feelings. He announced their breakup via the social media site and also updated followers on her Teen Choice Awards comments.
"You'll only know 1 side of the story RE Teen choice awards because I choose not to talk to the papers about every aspect of my personal life," he wrote.
"But just know I had a damn good reason (sic)."
Rita was candid about the situation when she was interviewed by Ryan Seacrest. She remained diplomatic but wishes she'd been given more notice about having to pull out of the show.
"For anybody who doesn’t understand how it works, he wrote and produced the song," she said.
"So he has to approve anything TV-wise for anybody who doesn’t get it. And obviously he owns the rights to it and he didn’t approve the Teen Choice Awards.
“I could have got told a few weeks earlier, you know. That would have been nice. It was a last-minute change, but you know what, it happens and we move on and move forward… It is what it is, man."
It's not the first time Rita has had an acrimonious breakup in the spotlight. In 2012 she dated Rob Kardashian for a short while, and the sock designer publically accused her of sleeping with other men while they were together.