A source recently told ET that the two have "no plans to start dating each other exclusively."
"Miley and Cody have been friends for years," the source adds. "They have hooked up in the past... They both just want to have fun and are open and honest with each other about that. Miley and Cody talk to each other about everything. They are very close and feel comfortable sharing details with each other about their lives."
So where did this relationship begin? ET looks back at the romance in the making:
Simpson told Fuse that Cyrus was his "childhood celebrity crush" long before their friendship even began.
“I knew all the words to her songs, I’m not gonna lie. I’m not ashamed about it, at all,” the Aussie singer said at the time. “I was a big Miley Cyrus fan. I think she will be, forever, the most dateable Disney star.”
"She's definitely at heart a very sweet, normal, cool girl," he said. "We were spending time out at her ranch in Nashville last week and I'm like, 'Why do people say these things?' She's just the coolest chick."
At the time, Simpson was dating model Gigi Hadid and Cyrus was dating Patrick Schwarzenegger. The pals ran in the same circles and attended several events together, including Simpson's birthday bash, where Cyrus was snapped holding the cake.
Simpson spoke about his friendship with Cyrus inGQ Australia, saying, "Miley is one of my best friends and she helps with some of that transitional stuff -- trying to escape your childhood. She's super open-minded and I'm working on becoming more like that."
Flash forward four years! Cyrus has split from Hemsworth, her husband of seven months, had a whirlwind romance with Carter, and split from her as well last month. Then in early October, Cyrus and Simpson were photographed kissing while getting some açaí bowls and the pics quickly circulated on the internet as did the rumors.
As the speculation started swirling and the commenters started trolling, Cyrus took to Instagram to make her feelings about the situation quite clear.
"I am grown now and make choices as an adult knowing the truth/details/reality," she wrote. "People only 'know' what they see on the internet."
The "Slide Away" singer went on to defend herself, writing, "Men (especially successful ones) are RARELY slut shamed. They move on from one beautiful young woman to the next MOST times without consequence. They are usually referenced as 'legends,' 'heart throbs,' 'G,' Ladies Man' etc..... where women are called sluts/whores! I am trying to just THRIVE/survived in a 'mans' world.... If we can't beat em, join em! If our president can 'grab em by the p***y...' Can't I just have a kiss and açaí bowl?!?!"
Shortly after, Simpson shared a kissing photo with Cyrus to his own Instagram account and calling her "baby," prompting the former Hannah Montana star to post her own throwback "baby" photos of herself.
Things took a turn for the serious when Cyrus got tonsillitis. Simpson was there, playing guitar, to try to nurse her back to health. And when she ended up getting hospitalized, he arrived with his trusty guitar and a bouquet of flowers. He even penned a song specifically for his lady love, which she encouraged him to release.