Why Is Katy Perry Down on Rihanna?
PHOTO: Rihanna and Katy Perry in the audience at the 54th Annual Grammy Awards, Feb. 12, 2012 in Los Angeles.

(Larry Busacca/Getty Images)

Katy Perry and Rihanna were once BFFs, but now, a man reportedly has come between them: Chris Brown.

Us Weekly reported that because of Rihanna's rekindled romance with Chris, their friendship isn't what it used to be.

"They aren't tight anymore because Katy doesn't approve of Rihanna dating Chris," an insider told the magazine.

At the Grammy Awards last Sunday, Perry, 28, and boyfriend John Mayer, 35, were sitting in the front row, while Rihanna and Brown were sitting in another part of the audience. At past Grammys, the two girls had sat right next to one another.

A representative for Perry did not immediately respond to's request for comment.

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It was also recently reported that Rihanna had fallen out with Perry because she didn't approve of Perry dating known womanizer Mayer. When asked about this by Rolling Stone magazine, Rihanna dismissed the report, and laughed, "Katy Perry can date anyone she wants. Besides, who the f*** am I to say anything? I could never given relationship advice to anybody!"

One of the most talked about moments of this year's Grammys was when Brown, 23, and Rihanna, 24, were spotted smiling and cuddling. The two walked the red carpet separately but once inside the Staples Center, they got cozy, when Rihanna, decked out in a red dress, photographed leaning her head on Brown's shoulder with a huge smile. The two lovebirds have come a long way in just four years.

On the eve of the 2009 Grammys, Brown assaulted Rihanna, whose bruised face became a tabloid fixture. Brown showed up to a court appearance Feb. 6 in Los Angeles on issues related to his probation with Rihanna by his side.

RELATED: Chris Brown Shows Up to Court With Rihanna

In a recent interview with Rolling Stone, Rihanna said public opinion doesn't matter.

"I wasn't going to let anybody's opinion get in the way of that. Even if it's a mistake, it's my mistake," Rihanna told the magazine, out Friday. "After being tormented for so many years, being angry and dark, I'd rather just live my truth and take the backlash. I can handle it.

"When you add up the pieces from the outside, it's not the cutest puzzle in the world," she says. "But it's different now."

SEE MORE: Rihanna on Chris Brown: 'We Know Exactly What We Have Now'

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