Katy Perry sounded wistful about romance on Friday, March 22. Three days after Us Weekly broke news of her breakup with John Mayer, the pop songstress, 28, shared a sad love song with her nearly 34 million Twitter followers. "Perfectly put, by Tristan Prettyman," Perry wrote, sharing Prettyman's piano-driven breakup ballad "I Was Gonna Marry You."

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But according to multiple sources close to Perry and Mayer, 35, the split seemed inevitable. On top of many work commitments -- Perry's third studio album, Mayer's upcoming tour dates -- the on-and-off couple have been "fighting" recently, one source close to the "Heartbreak Warfare" rocker says. Dating since July with a brief August split, the pair seemed to fast-track things in late 2012 and early 2013, with Perry spending time at his Montana ranch and Mayer celebrating the holidays with her family in Santa Barbara.

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"Introducing her to his dad was a big deal," the Mayer source says. "It was just too much, too soon," another insider adds.

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Still, some are cautioning that the pair could reconcile. "They've broken up before so it's hard to tell," a pal points out. "She's changed a lot since she's been with him . . . [you] can't argue that she has been in love."

This article originally appeared on Usmagazine.com: Katy Perry, John Mayer Were "Fighting" Pre-Split