Forget Lipstick On His Collar! Katy Perry Caught John Mayer Red Handed

Having gone through a horrific marriage slash divorce, we really wanted Katy Perry's ill-fated romance with Hollywood man whore John Mayer to work out, but it seems John just couldn't help but live up to his reputation.

The former-lovers, who began dating eight months ago, seemed to be going from strength to strength, until Katy found a napkin hidden in John's car with another woman's phone number written on it.

"John had picked Katy up in his vintage Land Rover so they could visit a Chihuahua rescue centre in the valley," an insider revealed to British magazine Grazia. "When they stopped for gas, Katy opened the glove compartment and found a phone number written on a napkin. One thing led to another and needless to say they never made it to the dog shelter. Katy called her assistant to take her home and they haven't spoken since." 

The couple had seemed so loved up...

Sources say a visit to Katy's religious parents first made John realise that he wasn't ready to commit to the Teenage Dream singer, after her father Keith Hudson reportedly told John to take care of his daughter.

Forget having a second phone, the classic number on the napkin trick is old-fashioned cheating at its finest... What a guy.