Jennifer Aniston Hits Boyfriend John Mayer's London Show

Jennifer Aniston snapped pictures of her boyfriend John Mayer as she watched him perform from backstage at Hard Rock Calling Festival in London's Hyde Park Saturday. "She was holding this big professional camera as he kicked off the set," a backstage witness tells Usmagazine.com. "As soon as he started singing she started taking photos. She was smiling and tapping her foot." (See photos of rocker romances.) The witness continues,"Jennifer must have taken about 10 photos during Mayer's set, and she would look at each one afterwards." "She was definitely into the music. Her foot was tapping and her body was swaying." When Mayer, 30, exited the stage, Aniston, 39, greeted him with some PDA. "She wrapped her arms around his neck," says the witness. (See what a body language expert had to say about their relationship.) How does Aniston's pal Sheryl Crow who performed at the event feel about the relationship? "If she's happy, then I'm happy!" Crow, 46, told Usmagazine.com. When recently asked about the romance, Mayer told USA Today, "All I can tell you is that I have made every decision in my life with complete authenticity. My feet are firmly on the ground. If you do things from the heart, it feels awesome." Tell Us: Do you think Jen and John are the real deal?