"Miley and Liam spoke very little after their separation and any communication was more about making decisions regarding plans and property," the source says. "They haven't been in touch in months and it has been for the best because they have both needed this time to heal and move on."
"Her divorce from Liam and her new relationship with Cody was a whirlwind of change for her, but in true Miley fashion she has come out on top," the source says, before describing Simpson as "lots of fun and a good friend to Miley."
"What began as close friends supporting one another during a rough time, blossomed into more," the source says. "Their relationship was unexpected and became meaningful very quickly, and she couldn't be happier. They are both very passionate about their music and it’s something that has bonded them."
Another thing that's positively impacted Cyrus' relationship with Simpson is her sobriety, which began after a vocal chord surgery last November.
"Miley's sobriety has made her very present in her relationship," the source says. "Her decision to be sober has changed the way she thinks about life. She would describe herself as a believer in this new way of life and is looking to make sobriety a long-term lifestyle."
Cyrus has big things in the works professionally as well, and "is excited for her first single to hit."
"She's thrilled to be getting back to work on her new album and she is really proud to share songs that have personal meaning to her," the source says.
On Sunday, she teased her new music on Instagram, writing, "Forever and ever no more. ? The #MidnightSky is the road I’m taking.... head high up in the clouds."