"We Are Never Ever Getting Back Together," from her upcoming album "Red," due out Oct. 22, originated with her complaints to songwriting partners MaxMartin and Shellback, she told "Good Morning America" Tuesday.
"This guy walks in who is a friend of my ex's and starts talking about how he's heard we're going to get back together," she said. "And that was not the case. So I start telling them the story: Break up, get back together, break up, get back together -- just, ugh, the worst! And I picked up the guitar and [Martin] said, 'This is what we're writing.' "