Who has Katy Perry ‘flipped out’ over?

Just when we thought these two had finally kissed and made up, rumours are now circling that BFFs, Rihanna and Katy Perry have fallen out again and this time, it seems to be over a boy.

Katy apparently lost it, when she discovered that RiRi was planning to record a duet with her ex, John Mayer.

Even though Katy has moved on and rumoured to be dating DJ Diplo now, a source said that she’s still hurt that Rihanna would betray her in this way.

“Katy’s been left shocked and hurt after finding out John and Rihanna met up at an LA recording studio two weeks ago before having dinner. But Katy’s flipped out and told her best mate she’s gone one step too far this time.”

It’s not the first time these two friends have fallen out, as Katy was not impressed with Rihanna, when she decided to get back together with her ex, Chris Brown.