And NOW there are whisperings that Katy Perry insisted on switching seats so that she wouldn't have to be ANYWHERE near Rihanna and Chris Brown!! It seems the ladies who were once BESTIES really have let a MAN come between them… This makes us sad all day. Ah well, at least Katy Kat could snuggle into the velvety shoulders of John Mayer for comfort… and hopefully girl didn't have to watch Riri and Breezy getting all up in each others cake cake cake during the show.  Jennifer Aniston has allegedly warned Katy Perry not to marry John Mayer. A source tells NOW magazine, ''Jen will never get past what John did to her. When they dated she really thought he was "the one", but it was horrific when he dumped her by text message. Having seen how serious they're getting, Jennifer told Katy not to believe his "pretty words". She's also urged Katy not to believe or accept any proposal unless she's absolutely sure he's changed.''