Robert Pattinson and John Mayer may be at odds over Katy Perry.

Robert Pattinson and Katy Perry are definitely good friends, maybe a little too good. Singer John Mayer is reportedly peeved that Pattinson is standing in the way of a reconciliation with the “Firework” singer.

And there may be more to it than a simple love triangle. Rob’s ex Kristen Stewart reportedly has gotten into the act, warning Katy to stay away from Rob.

Whether there is any truth to these star-crossed rumors remains to be seen. The source of both are tabloids that have a shoddy history for accuracy. Still, there is enough smoke to suggest there may be fire as well.

Kristen and Katy are friends and put on a public display of their affection at the Kids Choice Awards in March. But a lot has changed since then. Rob has walked out on Kristen and Perry and Mayer have broken up.

Now Kristen is reportedly shocked and upset that Rob and Katy are spending so much time together, according to InTouch magazine. Believe it?

“[Kristen] feels hurt,” a supposed insider claims. “She feels betrayed.” But Rob hardly seems to be in a position to strike up a relationship, since he’ll be leaving July 8 to film his next movie, “Maps to the Stars” in Toronto. He won’t be done until the end of August.

Mayer, 35, reportedly feels Pattinson is “getting in the way” of a reconciliation with Katy. “He was devastated,” when she dumped him according the Star, a UK tabloid. “He’s desperate to win her back.”

There could be some truth to that. Mayer has a terrible reputation when it comes to dating and after his own experience, Rob would like caution Katy to steer clear of the Lothario. “She certainly knows how it feels to go through a rough breakup or two!” the source said.

Mayer was spotted with her at her Memorial Day barbecue and he seemed to be trying his best to make her happy. “They were very flirty and having a really good time together. They have good chemistry.”

Katy seems to like bad boys, so who knows? Let us know your thoughts and follow TheImproper on Twitter for the latest Robert Pattinson updates you can trust.