Rupert Sanders wasn't the only person involved in Kristen Stewart and Robert Pattinson's breakup.
Life & Style can reveal that Katy Perry had quite an impact on her pal Rob's decision to end the four-year roller coaster romance.
"Katy told Rob she didn't think their relationship could withstand the cheating scandal," an insider tells Life & Style. "And he deserved better than someone who would destroy a family [like Rupert's]."
Robert Pattinson and Kristen Stewart Split
Though their relationship was rocked by Kristen's infidelity with her Snow White and the Huntsman director last summer, Rob was set on trying to make it work. The pair put on a united front when promoting The Twilight Saga: Breaking Dawn — Part 2 in November and seemed to be doing just fine attending parties and award shows together.
But just days after ringing in his 27th birthday on May 13, the pair officially called it quits — and Katy was there for him.
"I know he always leans on her during hard times, and Katy would do anything for him," the insider tells Life & Style.
The "Firework" songstress had been urging him to split from Kristen since the cheating scandal.
Robert Pattinson and Kristen Stewart's Rocky Romance Explained in 5 Photos
"Katy never really supported Rob's decision to get back with Kristen," says the source. "She liked Kristen, but ultimately she's loyal to Rob and wants what's best for him."
For more inside Kristen and Rob's split, pick up the new issue of Life & Style, on stands tomorrow.