“So Long, London” is rumored to be about Taylor’s British ex-boyfriend, Joe Alywn, whom she dated from 2016 to 2023. Throughout her tragic narration, Taylor hints at the possible reasons behind their breakup. These could be them drifting apart due to lifestyle differences, Alwyn’s suggested depression, him being unready for marriage, and/or Taylor’s emotional infidelity towards the end of their relationship.

Although many fans speculated unfaithfulness to be the cause of their breakup, Taylor does not mention it nor hints at it throughout the song. On the contrary, she suggests Alwyn’s struggle with his mental health to be the downfall. This was evident throughout her repeated chorus: “how much sad did you think I had? Did you think I had in me? How much tragedy?” Although it is unclear who ended the relationship, Taylor shared her dissatisfaction on how things turned out multiple times throughout the album, notably on “My Boy Only Breaks His Favorite Toys,” “Fortnight,” “loml,” and “The Black Dog.”

Famously, Taylor’s track fives are the most personal and vulnerable tracks on each album. This track was no different, with Taylor detailing her raw emotions as her 6-year relationship fell apart. This is the second time one of these emotional tracks has been produced by collaborator Aaron Dessner, following 2020’s “tolerate it.” This is also the second time Swift has used “London” in a track title. The first was “London Boy” off of 2019’s Lover, which is also about Alwyn.

Before the release of The Tortured Poets Department, it had been speculated that the length of the track would be 9:28, since 9/28 is Swift’s and Alwyn’s anniversary. However, this rumor was denied when the real track times came out.