jennifer aniston and john mayerEven though Jennifer Aniston and John Mayer are currently leading Fametastic’s Spring Fling poll, some of Jennifer’s friends are reportedly less convinced that John is the man for her and are worried that he’ll break her heart.

The couple went public with their romance at the end of April, when John visited Jennifer in Miami where she was filming Marley & Me and this weekend she’s been with the musician in the UK, while he’s been performing at the Brixton Academy and Hyde Park’s Hard Rock Calling two-day festival.

Jennifer was spotted taking photos of John’s Hard Rock set and when he exited the stage, she was spotted giving him a congratulatory hug and kiss.

However, a source close to the couple told the Mirror that John - who has previously dated Jessica Simpson and been repeatedly linked to Cameron Diaz - may not be after a long term thing with the former Friends star: “John likes to conquer the current ‘It Girl’.

“He aims for the ‘It Girl’ to make him the big guy in Hollywood, the guy on all the magazine covers.”

A second friend added: “He’s a real ladies’ man. It won’t last.”

But others in Camp Aniston are more positive about the relationship, saying: “Jennifer’s smart. She’s using John by letting him think he’s using her.”

And Jennifer’s close friend Sheryl Crow, who performed ahead of John on Saturday, told Us Weekly: “If she’s happy, then I’m happy!”