John Mayer and Katy Perry

John Mayer's new girlfriend Katy Perry has already had an effect on her new beau, a report claims the hunky singer has turned his back on his womanizing ways to commit to Katy after only a few dates.

The musician has dated a string of famous beauties in the past, including Jennifer Aniston, Taylor Swift and Jennifer Love Hewitt, and has earned himself a reputation as a ladies' man.

But John has had a ''heart to heart'' conversation with Katy after just several weeks of dating and has told her he wants their relationship to get serious.

A source told RadarOnline.com: ''John has had his eye on Katy for a while and he had to try and convince her that he was right for her.

''The best way he thought he could do that was by dispelling his past reputation as a lothario to Katy.

''He knew he had to change his ways if he ever wanted to get serious with somebody and he had a heart to heart with Katy, telling her he was desperate to change his ways.

''Katy believed him and now their relationship is moving on. She wants to visit his home in Montana and has slowly warmed to the idea that he's boyfriend material.''

The 34-year-old singer also now realizes his previous attitude to women made him a ''douchebag''.

John previously landed himself in hot water when he described ex-girlfriend Jessica Simpson as ''sexual napalm'' and said he was addicted to her ''like crack cocaine'' because she was so crazy in the bedroom.

The source added: ''He's never been short of female attention in the past and has always been quick to milk that at every given opportunity. But John realizes now that it made him appear a bit of a douchebag and an unattractive catch.''

Katy, 27, had her divorce from Russell Brand finalized on July 16 just months after the 37-year-old comedian filed papers in December 2011 after just a year of marriage.

Russell is now dating 'Dallas' star Jordana Brewster's sister, Isabella.

© Bang Showbiz