The emotional new track -- which is notably slower and somewhat more contemplative than the poppier "ME!" and "You Need to Calm Down" which she released in recent weeks -- was also released as a lyric video on Swift's YouTube channel.
The almost bittersweet melody and lovelorn lyrics tell a story of a relationship's trials, tribulations and the eventual perseverance of love.
Swift also makes multiple illusions to her "lover" in the song, and the timeframe presented in the lyrics strongly suggests the lines are in reference to her real-life boyfriend, Joe Alwyn.
"We can let our friends crash in the living room/ This is our place, we make the call/ And I'm highly suspicious/ That everyone who sees you wants you," she sings. "I've loved you three summers now, honey, And I want them all."
She also evokes wedding imagery, with lines like, "Ladies and gentlemen/ Will you please stand/ With every guitar string scar on my hand/ I take this magnetic force of a man/ To be my lover."
The tune also imagines what the narrator's life will be like with her lover over the years. It's likely fans who believe she and Alwyn are already engaged may take particular interest in these lyrics.
Swift's upcoming album, Lover, is set to drop Aug 22.