The singer released her second 'from the vault' song on Wednesday.
One of six new-to-fans songs, which were written at the same time as Swift's other tracks on her 2008 album, "Mr. Perfectly Fine" certainly fits in that era, as it's about a guy who lied about his intentions and moved on with someone new.
Fans loved the track on first listen, largely because it, like much of Swift's older music, led to speculation about the potential subject of the song. Swift herself acknowledged that fact in a tweet announcing the track's release.
"Me in 2020: life is chill, writing songs based in fiction to avoid drama, feeling pretty grown up. My 2008 music from the vault, in a goblin voice: 'REELEEEEEEASE MR PERFECTLY FIIIIIIINE,'" she wrote.
Chatter only grew when Sophie Turner praised the song on her Instagram Story, writing, "It's not NOT a bop."
"Forever bending the knee for the [queen] of the north," Swift responded, referencing Turner's Game of Thrones character.
The exchange caught fans' attention, as many have begun to speculate that "Mr. Perfectly Fine" is about Turner's husband, Joe Jonas, whom Swift dated for three months in 2008.
A source tells ET that Turner "is a fan of Taylor and loves her music. The song 'Mr. Perfectly Fine' is about a former, old romance, so if it is about Joe Jonas, Sophie doesn't mind as Joe and Taylor dated over a decade ago."
The source adds that "Taylor is happy where she is at in her life, both personally and professionally, and is happy to be friends with Sophie and Joe. She appreciates Sophie's support and thinks Sophie is extremely talented as well."
Meanwhile, fans loved the fact that Turner was enjoying Swift's track, with one writing, "Big lols that Sophie Turner, Joe Jonas’s wife, is bopping to Taylor Swift’s new song, also about Joe Jonas, on her insta story, the girl energy we all need x"
As for why fans believe the song is about Jonas, it all comes down to the lyrics.
After Swift and Jonas called it quits in 2008, she appeared on The Ellen DeGeneres Show, and called him out for ending their relationship with a 25-second phone call. At the time, Jonas reportedly reacted to Swift's interview with a post on MySpace.
"Anytime you are in a relationship for any length of time there are going to be issues," he wrote in part, according to Us Weekly. "Sometimes they resolve, other times they lead to a change of heart; this was the case recently."
It was Jonas' "change of heart" comment that got fans' attention, because, on "Mr. Perfectly Fine," Swift sings, "That was when I got to know Mr. Change of heart / Mr. Leaves me all alone / I fall apart / It takes everything in me just to get up each day / But it’s wonderful to see that you’re OK."
Also during her Ellen interview, Swift revealed that one of the tracks on Fearless, "Forever and Always," was about her and Jonas' split. In that song, Swift sings, "You looked me in the eye and told me you loved me... / One second it was perfect, now you're halfway out the door."
Fans related the entire premise of "Forever and Always" to "Mr. Perfectly Fine," though they specifically cited the latter's line, "Mr. looked me in the eye and told me you would never go away."
Another lyrical clue that points to Jonas as the subject of Swift's new track, comes in one of the verses of "Mr. Perfectly Fine."
"So dignified in your well-pressed suit / So strategized / All the eyes on you / Sashay your way to your seat / It’s the best seat / In the best room / Oh, he’s so smug / Mr. Always wins," she sings.
Shortly after Swift and Jonas called it quits, they both attended the American Music Awards. At that ceremony, Jonas, dressed in a black suit, and his brothers were seated near the stage, as their band took home the New Artist of the Year trophy.
Fearless (Taylor's Version) is due out April 9.