The reason exposed by John behind this break up is that he is “tired of Perry’s hard partying and decided to pull the plug”.
A friend told Us Weekly magazine: “He dumped her over email. She was furious and really hurt.
"She was into him, but he wasn’t feeling it.”
The pair split up last week after just a few weeks of casual dating.
The budding romance was first reported in June when Katy, who had previously admitted to a crush on the rocker, was seen snogging 34-year-old John during an "affectionate" appearance at Soho House in West Hollywood.