Katy Perry's friends are shocked she has rekindled her relationship with John Mayer.

The 'Dark Horse' hitmaker has enjoyed ''numerous dinner dates and sleepovers'' with the 37-year-old singer in recent weeks, but their reunion came as a surprise to the 30-year-old beauty's close pals.

A source said: ''[It's] a complete 180 from where she was weeks ago.''

Katy ended her on-again, off-again romance with John last February as they clashed over how to manage their relationship while she was away on her 'Prismatic' world tour.

The insider said: ''They're both outspoken and independent. It draws them together, but it can cause problems at times.''

But they are determined to make their relationship work this time round.

The source told PEOPLE magazine: ''They are in love and have been seeing each other for a while. They missed each other.

''They seem very happy about being back together again. [But] they have to make time for each other and figure out how they can be together in a smooth relationship.''

Sources previously suggested John was ''jealous'' of Katy's success and the 'Roar' singer recently admitted most of her former boyfriends were ''threatened'' by her career.

In October, she said: ''A lot of times I've ended up with people who have been intimidated by me, unfortunately. They say they're not, but it comes out in the long run. They're threatened, or there's resentment because they don't know how to handle it.''