By Aly Semigran
Oct 24, 2014 @ 8:27 am

If you could have anyone write a song about your love life, it would have to be Taylor Swift, right? Well, that's definitely the case for the Grammy-winning singer's good pal, Girls star Lena Dunham. Swift stopped by Jimmy Kimmel Live! on Thursday, where she broke down the lyrics to one of her songs, which Kimmel assumed was about one of her relationships. The lyrics read, "One night, he wakes / Strange look on his face / Pauses, then says 'You're my best friend.' / And you know what it was. He is in love."

But instead of drawing from her own experiences, Swift explained that she loosely based the song after Dunham and her musician beau Jack Antonoff (Fun.'s guitarist, who co-wrote the track). "It's a commentary on what their relationship has been like," she said.

Swift, who looked ravishing in red, chatted more with the host about some of her other tracks before she performed two of her new tunes from her new hit album 1989—after an outfit change, of course!

Watch Swift and Kimmel's lyrical breakdown in the above video, then follow it up with the star's performances of "Out of the Woods" and "Shake It Off" here: