Angelina Jolie fears Brad Pitt's assistant Lara Marsden will steal him?

Angelina Jolie is reportedly worried that Brad Pitt's 25-year-old assistant Lara Marsden will steal Brad while he films World War Z!

"Brad spends a lot of time with Lara when he isn't filming," a source tells Star. "Lara looks after Brad, making sure he is well taken care of and getting him whatever he needs. She even bring tea to his 25-foot white luxury trailer in between scenes."

"You can definitely hear snickers and giggles from the crew members when Lara visits Brad's trailer alone," the source adds.

"Angie's been making her feelings about Brad's relationship with Lara known for months," another insider explains. "So when she found out Brad was still getting cozy with her, Angelina absolutely flipped!"

"Angelina was so upset she even kicked Brad out of their house, screaming 'Get out!,'" the source continues. "She was ranting and raving, threatening to pack up and take the kids away. Now she's barely speaking to him."