Taylor Swift collaborated with several people for folklore, but it turns out one of them is extra close to her heart! As Entertainment Tonight shares, Swift addressed a long-speculated fan theory in her new concert documentary, folklore: the long pond studio sessions, explaining that her co-writer "William Bowery" is none other than her boyfriend, Joe Alwyn!

Swift talks about Alwyn's musicality and creativity

Swift is known for including 'easter eggs' in the content she creates— fun little nods to things that are meant for fans to pick up on. And in folklore: the long pond studio sessions, the singer confirmed that one such tidbit of information could be found in the name of one of her co-writers— the enigmatic "William Bowery"! When fans realized that Bowery wasn't a known songwriter, they did some research.

As Entertainment Tonight mentions, "Bowery" is the name of a hotel Swift and Alwyn were seen outside of, and "William" is the first name of Alwyn's great-grandfather! "There's been a lot of discussion about William Bowery and his identity," Swift tells collaborators Aaron Dessner and Jack Antonoff in the film. "William Bowery is Joe, as we know. And Joe, Joe plays piano beautifully, and he's always just playing and making things up and kind of creating things." 

Taylor Swift at the TIME 100 Gala 2019

Swift shares that Alwyn helped compose "betty" and "exile"

Swift said that the first musical collaboration between herself and Alwyn came about unexpectedly! "I just heard Joe singing the entire, fully formed chorus of "Betty" from another room. And I just was like, 'Hello,'" she said. "It was a step that we would never have taken because why would we have ever written a song together?"

She mentions that the idea to write the song from the male perspective of a character she invented named "James" actually stemmed from Alwyn's involvement! "He was singing the chorus of it and I thought it sounded really good from a man's voice, from a masculine perspective," Swift shared. And as it turns out, "betty" wasn't the only song that Alwyn was involved in!

"'Exile' was crazy because Joe had written that entire piano part and he was singing the Bon Iver part... He was just singing it. And so, I was entranced and I asked if we could keep writing that one," Swift said. "It was pretty obvious that it should be a duet, 'cause he's got such a low voice and it sounded really good sung down there in that register."

Swift's folklore: the long pond studio sessions was released on Disney+ on Wednesday, and it sees her performing and discussing her newest material! The singer surprised fans when she dropped folklore back in July, and she recently picked up 6 GRAMMY nominations for the critically-praised album!