"John has had his eye on Katy for a while and he had to try and convince her that he was right for her," a source revealed to Radar Online. "The best way he thought he could do that was by dispelling his past reputation as a Lothario to Katy.
"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.
"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 source revealed.
Mayer, 34, and Perry, 27, were reportedly "all over each other" at a friend's pool party. Radar Online said the "Teenage Dream" star was sitting on Mayer's lap while they made out like they "were on a honeymoon."
Though she might be happy now, it was only July 16 that Perry's divorce from ex-husband Russell Brand was finalized, the site noted.
Comedian and actor Russell Brand filed for divorce citing "irreconcilable difference" in December 2011.
Perry isn't the only one who's moved on. Her ex-husband Brand is supposedly in a relationship with "The Fast and the Furious" Jordana Brewster's sister, Isabella.
Do you think John Mayer has really "changed his ways" for Katy Perry?