Katy Perry ‘acting like a teenager’

Katy Perry's friends are reportedly worried that she is acting more like a "teenager" than a "world-famous pop star".

Katy is currently enjoying an on-off relationship with John Mayer, who has a reputation as a Hollywood heartbreaker. John has famously dated a string of stunning stars including Jennifer Aniston, Taylor Swift and Jessica Simpson.

Katy has apparently been warned off the ladies’ man, but has ignored advice from friends.

"Katy's friends worry that she's acting like a teenager rather than a world-famous pop star. Many thought she'd steer clear of John after he made it clear there wasn't a future between them, but she doesn't seem to care," a source told British magazine Heat.

"Katy just can't seem to let him go, despite her friends begging her to dump him. Despite his reputation, Katy loves John's company."

Katy is enjoying her single status since her divorce from British comedian Russell Brand was finalised in July this year.