Friends stars Jennifer Aniston and Courteney Cox have been famous for being real-life friends ever since the show debuted in 1994. So why haven't they been photographed together in almost a year? Sources tell Us "there's tension" between them, and not because Courteney had dinner with Brad Pitt last month. No, it stems from Cox going out on the town with her male costars during her trial separation from hubby David Arquette.
"Jen thinks Courteney is acting callous by running around with this guy but refusing to file divorce papers," an Aniston source says. "Like she's playing mind games with David." The source adds that the whole thing reminds Jen of her own ex-husband taking up with Angelina Jolie after they split: "She hates watching Courteney do the same thing." But click here for a report that Jen recently introduced her new boy toy to friends ... including Cox. (Read more Jennifer Aniston stories.)