And he responded by writing a song that slammed his ex.
But the bad blood between these young stars appears to have simmered down, as Jonas said in an interview with Washington, D.C.'s 94.7 Fresh FM yesterday that Swift's latest breakup anthem - "We Are Never Ever Getting Back Together" - is not based on their history.
"I don't think we've ever tried [to get back together] another time, so I can tell you it's not about me," he said. "That said, I think the song is great. Taylor does pop music really well and I'm happy for her."
Are the two now on speaking terms? Not really. However:
"I haven't really spoken to her recently, but I was able to go to her concert last year, and her show live is so phenomenal," Jonas added. "I would say anybody should go see it if they haven't had a chance."
Swift is now dating Conor Kennedy, but fans are more focused on her past than her present. With Jonas out of the running, we remain convinced this track was penned about Chord Overstreet.