Now we don't actually know that for sure. Swift herself never officially names names, but even without the all-important album liner notes -- where she often drops extra hints -- there are plenty of lyrical clues that point to The One With The Man Bun.
Taylor Swift's 'Out Of the Woods' Has Arrived…with Lyrics: Listen
Let's make like Nancy Drew and break down some of the most revealing "Out of the Woods" lyrics, ranked from could-be-mere-coincidence (1) to pretty dang convincing (4).
1. "We were built to fall apart/ Then fall back together"
This lyric implies an on-again, off-again relationship, which -- based on the amount of tabloid headlines the brief romance generated -- definitely seems accurate.
2. "Last December..."
While Swift's most famous December-related paramour was Taylor Lautner (See: Her missing his "tan skin" in "Back To December"), this clue could also point to Harry. The two allegedly had a big fight in December 2012, which ultimately led to their breakup (and Swift's super-sad solo boat ride).
3. "Remember when you hit the brakes too soon/ Twenty stitches in a hospital room"
Remember when Swift and Styles went snowmobiling together in a much-publicized trip to Utah with Justin Bieber? Rolling Stone wrote about these lyrics: "She says it was inspired by a snowmobile ride with an ex who lost control and wrecked it so badly that she saw her life flash before her eyes."
4. "Your necklace hanging round my neck/ The night we couldn't quite forget/ When we decided/ To move the furniture so we could dance/ Two paper airplanes flying, flying"
While the duo were rumored to be together, the two wore identical plane necklaces.
What did we forget? Please post all working "Out of the Woods" theories in the comments.