The 24-year-old singer opened up in the May 13 issue of Billboard about Hemsworth, 27, and how their relationship influenced her new album.
"I needed to change so much," she said of their breakup. "And changing with someone else not changing like that is too hard. Suddenly you're like, 'I don't recognize you anymore.' We had to refall for each other."
Cyrus and Hemsworth reconciled in January 2016 after ending their engagement in September 2013 after four years of dating. Cyrus' forthcoming single, "Malibu," is a love song inspired by the Hunger Games actor.
"[I wrote it] on the way to The Voice," she shared. "I drive myself everywhere, but that day I decided to Uber, and I was trying not to sing out loud because someone else was in the car."
"They're going to talk about me if I come out of restaurant with Liam. So why not put the power back in my relationship and say, 'This is how I feel?'" the star added of the personal song.
"Malibu" will debut May 1 ahead of Cyrus' sixth studio album. The singer, who last released Miley Cyrus & Her Dead Petz in 2015, couldn't help but gush over Hemsworth in a birthday post in January.
"Happiest birthday EVER to my favorite being EVER EVER EVER! You have been my best friend since the day we met..... I am beyond lucky to share sooooo many animals with you!!!" she wrote of their many pets. "I love you @liamhemsworth."