Cyrus and Simpson have been packing on the PDA for the past week, ever since they were spotted kissing over açaí bowls following the "Wrecking Ball" singer's splits from husband Liam Hemsworth and girlfriend Kaitlynn Carter.
They have hooked up in the past," the source said. "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."