We couldn't help but notice the seating arrangements at this year's Grammy Awards.

Last year, onetime BFFs Katy Perry and Rihanna sat next to each other giggling and smiling. However, this year, Perry brought "Girls" star Allison Williams as her date, while Rihanna cozied up to Chris Brown.

Though it was just four years ago that Brown brutally assaulted Rihanna before the Grammy Awards, the 24-year-old singer has forgiven him and confirmed that the two are together again -- which allegedly isn't sitting well with Perry.

Sources told Us Weekly that Perry "doesn't approve" of Rihanna's decision to get romantically involved with Brown again, and their friendship has suffered because of it.

This isn't the first time we've heard reports that Perry and Rihanna have let Brown come between them. In November, the New York Daily News reported that the two were "barely talking."

At the time, a source close to Perry revealed "there has been tension" between the pop stars since Rihanna reunited with Brown, and noted that Rihanna even skipped out on Perry's Halloween party. Perry, like many others, fear that Rihanna is "making a huge mistake and doesn’t want to be part of it," revealed the insider.

Though neither pop star has commented on rumors of their rift, we also couldn't help but notice the last time we saw the former BFFs together was at the MTV Video Music Awards in September --he same award show where Rihanna publicly planted a kiss on Brown.