Hemsworth, now 22, eventually got the part -- and the film's leading lady.
"What happened happened, and we've been together two and a half years," Hemsworth says. "She makes me really happy. When you start, you want to be professional, but when you're filming those scenes with someone and pretending to love them, you're not human if you don't feel something."
When filming wrapped, The Hunger Games star went back to Nashville with Cyrus and her famous family. "[Billy Ray] is very spiritual," Hemsworth says. "He's just one of the nicest guys. Very accommodating. I've listened to his music since we got together. It's awesome."
The Southern family also introduced him to Cracker Barrel. "I'd never heard of country-fried steak before. It's great!" Hemsworth raves. "I love fried food."
Not every aspect of Hemsworth's relationship is so picture-perfect. When Cyrus joked that she "smokes way too much f-cking weed" at her 19th birthday, the video went viral -- and Hemsworth became livid.
"She's in a room full of her best friends," the actor tells Details. "And you have one person who comes in there and videos it. The poor girl can't have one night where she can feel safe in her own world. It's ridiculous."