Singer Katy Perry is friends with Kristen Stewart and Robert Pattinson, but when the collective Robsten broke up, Perry started spending a lot of time with Pattinson -- so much so that lots of people are wondering if they're hooking up.

And Stewart is none too pleased.

While Kristen is supposedly being consoled by break-up veteran Taylor Swift, Rob has retreated to the soft comforting bosom of Katy. Which, given the choice, we'd probably pick too.

The dynamic duo have since been spotted crashing wedding rehearsals of complete strangers (which seems to be the latest trend) and attending concerts together.

"[Kristen] feels incredibly down right now and betrayed," an insider told the Daily Mail, reporting that Stewart has broken off all communication and taken a step back after hearing reports that "Roberry" might be a thing.

However, a source close to Rob says he and Katy are just friends, and she's just there as a shoulder (or pair of breasts) to cry on.

"Kristen is in a certain state of denial. She can't let go of Rob or get over him," the insider continues. "She keeps trying to contact Robert and find out what he is doing but her attempts to see Rob have been rebuffed. Rob is not responding to her."

No word from Katy's camp, but we're guessing she's too busy rekindling things with John Mayer to care about any of this.

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