Taylor Swift’s feud with Katy Perry started over John Mayer

Taylor Swift’s feud with Katy Perry did start over a guy — and sources tell Page Six it was John Mayer.

After Swift mentioned a “straight-up enemy” about whom she’s written a new song, “Bad Blood,” in an interview with Rolling Stone, Perry tweeted to call out a mystery mean girl, “Watch out for Regina George in sheep’s clothing.”

Swift said in the interview, “Oh, we’re just straight-up enemies. And it wasn’t even about a guy! It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me . . . I don’t think there would be any personal problem if she weren’t competitive.”

Taylor and Mayer had a love affair in 2010 before he dumped her.

She released the song “Dear John” with lyrics, “Don’t you think 19’s too young to be played by/Your dark twisted games.”

In 2012, Perry started dating Mayer, who said he was “really humiliated” by Swift’s song. Music sources told Page Six, “Perry started making digs at Taylor from then on.”

While it was reported that several dancers left Swift’s tour for Perry’s last year, Swift appeared to confirm earlier tensions between them, telling Rolling Stone, “For years, I was never sure if we were friends or not. She would come up to me at awards shows and say something and walk away, and I would think, ‘Are we friends, or did she just give me the harshest insult of my life?’ ”

Reps for the two singers, who were seated in different sections at the recent VMAs, didn’t get back to us.