Cyrus began dating the fellow musician and actor after separating from her former husband, actor Liam Hemsworth.
The 28-year-old’s song “Midnight Sky” is said to be about her breakups from Hemsworth, Simpson, and blogger Kaitlynn Carter.
It includes the lyrics: “I was born to run, I don’t belong to anyone/ I don’t need to be loved by you.”
“Everything ended fairly amicably,” Simpson, 24, told Australia’s 60 Minutes of their split in August 2020.
“It was just one of those phases you go through, I guess, and you learn a lot from it.”
He also explained that he and Cyrus had been “good friends” before they began dating.
Addressing their split at the time, Cyrus said in an Instagram Live: “Two halves can’t make a whole and we’re individually just working on ourselves to become the people that we wanna be, like everybody else at this age.”
She added: “We’ve been friends for 10 years and we’re going to continue to be friends, so just don’t make it something that it is not.”
Cyrus’s latest album, Plastic Hearts, received positive reviews from critics and charted at No 4 in the UK. Read The Independent’s review here.