John Mayer jealous of Katy Perry's friendship with Russell Brand?

John Mayer was allegedly jealous of ex-girlfriend Katy Perry's relationship with her former husband Russell Brand.

According to Radar Online, Mayer was unhappy that 'Last Friday Night' singer Perry was still in touch with comedian Brand, and that the pair were on friendly terms.

Katy Perry, John Mayer

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John Mayer and Katy Perry

A source told the website that the relationship between Mayer and Perry, who were together for seven months, was like "a volcano just about to go off", adding: "Their relationship was incredibly volatile, stemming from the jealousy they both harboured deep inside.

"Sure, Katy was unhappy that John constantly flirted with other girls and played up his heartbreaker image, even when she was standing next to him. But Katy gave it back.

"She knew that she could push John's buttons by comparing his flaws to what she saw was great in Russell, which he hated!"

The source also claimed that Perry and Brand, who divorced after 14 months of marriage, still spoke to one another - something that apparently "irked" 35-year-old Mayer.

Katy Perry, Russell Brand

Katy Perry with ex-husband Russell Brand

Mayer confirmed on Tuesday (April 2) that he and Perry had split. The 'Gravity' singer told chat show host Ellen DeGeneres that he had been "much happier" since his relationship with Perry ended.

"I'm on the same journey as everyone else," continued Mayer. "Coupling is a tricky thing. It's a tricky thing. I want everyone to be happy."

Meanwhile, it was recently reported that Perry has "had enough of men" since splitting with Mayer.

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