Jennifer Aniston We've all been there...

You find yourself a hot new fella, who you think is just swell.

But then you introduce him to your mates and he just ain't their cup of tea.

And now Jennifer Aniston in getting that treatment too, with her new man John Mayer.

Her friend told Us mag: "He's a real ladies' man. It won't last."

But let's face it, friends are always fearful - and he's had dalliances with quite a few Hollywood fillies, including Cameron Diaz and Jessica Simpson.

Jen certainly seems the smitten kitten and the pair have been papped in a taxi in the early hours of Saturday morning after John's gig at London's Brixton Academy.

Later that day she slipped into the backstage area at Hard Rock Calling in Central London, and took snaps of him playing.John Mayer

The word is that her buds are worried that she's heading for another heartbreak with the man dubbed "John Mayer, Hollywood Player" back home in LA.

A source told the Daily Mirror: "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."

But not all her mates are against the coupling another friend added: "This is a whole new Jen.

"Unlike Jessica, she waits days before texting him back.

"Jennifer's smart. She's using John by letting him think he's using her."

Cripes, how complicated.