Angelina Jolie having affair with bodyguard?

Angelina Jolie's relationship with partner Brad Pitt is under strain over claims that she's fallen for her British bodyguard.

The actress has a close friendship with her security guy, Billy aka ‘Chisel' because of his toned torso.

“Angie used to use Mickey Brett, their main security person, for her routine bodyguard work,� a friend of Brad and Angie's tells Now magazine. “But recently this new guy- a younger, better-looking one- has been handling day-to-day outings with Angie.�

Billy, says an insider, is in his 40s (like Brad), is Scottish and has worked with the British Secret Intelligence Service. Naturally, as an ex-commando, the hunk is super-fit and lifts weights and runs for at least an hour a day.

“Brad and Angie trust him with their lives and the lives of their children,� the insider tells Now.

The couple's friend says Brad has noticed Angie and Billy laughing like close friends, and this makes him uncomfortable.