Katy Perry and Rihanna are not hanging out as much lately. But, why?

It all has to do with Chris Brown. Katy is pretty sad that Rihanna got back together with him after he hurt her so badly.

Rihanna and Katy used to be really close. When Katy was married to Russell Brand the four of them (Katy, Rihanna, Russell and Chris) would get together pretty often and spend time together.

No word on if the duo are in a disagreement or if they have just grown apart.

Let's hope they can work through this!