The track, which features Bon Iver, was released two years before Kardashian and West started dating in 2012, but apparently West got the lyrics directly from a card he wrote for his then-friend's 30th birthday.
"Happy 10 year anniversary to Kanye's 'My Beautiful Dark Twisted Fantasy' album," Kardashian wrote in an Instagram post Sunday. "For those that don't know the story behind 'Lost In The World'... Kanye couldn't come up with some of the lyrics but then realized he had then [sic] in a poem he had written me that was my birthday card he gave me for my 30th birthday. He took the poem he wrote me and made it the song. I keep everything!"
Looking back, it's easy to wonder whether the poem-turned-song-lyrics hinted at West's feelings for Kardashian, but at the time, the reality star was in a relationship with NBA player Kris Humphries. Kardashian and Humphries got married in a live television event in August 2011, but split 72 days later in October.
"You're my devil, you're my angel / You're my Heaven, you're my Hell," the artist raps on the track. "You're my now / you're my forever / You're my freedom, you're my jail / You're my lies, you're my truth / You're my war, you're my truce."
This wasn't the only time West referenced the early days of his relationship with Kardashian in his music. On his track 2012 track "Cold" off the album "Cruel Summer," he raps about falling for Kardashian while she was dating someone else.
"And I'll admit, I had fell in love with Kim / Around the same time she had fell in love with him," he rapped. "Well that's cool, baby girl, do ya thang / Lucky I ain't had Jay drop him from the team."
Now, Kardashian and West are a power couple with four children – and West's songs are a time capsule of their early love.