*Rihanna’s rekindled relationship with Chris Brown has allegedly put a strain on her friendship with her best friend Katy Perry.

Katy, who has been busy stumping for President Obama in recent weeks, was missing from Rihanna’s Halloween party, and Rihanna failed to show at Katy’s birthday party. According to reports, Katy thinks Rihanna is “making a huge mistake” by returning to the ex-boyfriend who beat her.

“They’re barely talking and ever since the couple reunited, there has been tension between them. Katy has been spending a lot of time with pals Robert Pattinson and Kristen Stewart. Katy fears Rihanna is making a huge mistake and doesn’t want to be part of it,” a source in Katy’s camp tells [email protected]

The last time Katy and Rihanna were spotted together, publicly, was during the MTV Video Music Awards where Rihanna publicly planted her first kiss on Chris since their break up in 2009.