Taylor Swift Wrote Rihanna & Calvin Harris' 'This Is What You Came For'

Update 12PM ET: Taylor Swift's rep confirmed that she co-wrote Calvin Harris and Rihanna's "This Is What You Came For."

Original: Swifties and non-Swifties, take this with a grain of salt, but there's yet another theory about why Taylor Swift and Calvin Harris, together for 15 months, broke up. According to TMZ, Swift is mad because she secretly wrote Harris and Rihanna's "This Is What You Came For," but Harris was weird about saying if he'd collaborate with his girlfriend in interviews.

Yeah, juicy, right? Apparently (*uses hushed gossipy voice*), Taylor cut a demo of the song with a piano and her iPhone and sent it to Calvin, who then produced the song into something much larger. They both agreed that being on a song together wasn't the best career move (keep in mind, the last time Swift collab'd with a boyfriend was on John Mayer's "Half of My Heart" in 2009, and it will go down in history). So she retained credit for "This Is What You Came For" under a pen name, Nils Sjoberg.