Dolly Parton knows a thing or two about lasting love!

The country music icon will celebrate her 50th wedding anniversary with husband Carl Dean later this year, and she's revealing to ET the secret to their enduring marriage.

"We've just always been great friends," she told ET's Nischelle Turner, flashing that million watt smile. "He's very much a loner. He likes his time alone, he likes his space. The fact that I'm gone a lot suits him fine! He likes it when I'm home, he likes it when I'm gone, and it's kinda the same with me. We just always had this wonderful relationship and a wonderful understanding about this whole thing."

WATCH: Dolly Parton Opens Up About Her Poor Upbringing and Why She Wouldn't Trade It for the World

The couple wed on May 30, 1966, nearly a full year before Parton debuted her first full-length album, Hello, I'm Dolly. The rest, as they say, is history.

Though Parton says she never doles out advice, she seems to be rooting for her goddaughter, Miley Cyrus, to have her own happily ever after with Liam Hemsworth.

"I was really happy when I heard they'd gotten back together, 'cause I know that seemed to be a big heartache for both of them when that happened," she said. "That's good that they're back together."

Cyrus and Hemsworth became engaged in June 2012, but went their separate ways in September 2013. In January 2016, Cyrus sparked rumors that the pair could be very much on-again, showing off her engagement ring in photos and popping up outside Hemsworth's Malibu, California, home with a U-Haul truck.

"Miley, she's great," Parton gushed. "She's a talent, she's deep, she's smart, she's sensitive, and she's gone through a lot -- she's put herself through a lot -- but she's gonna always land on her feet 'cause she's a gifted girl."

Like Cyrus, Parton grew up in the spotlight. Now, at 70 years old, the entertainer is still a force to be reckoned with. She's about to embark on her first full-blown tour in more than 25 years, in which she'll perform stripped-down versions of her biggest hits and a handful of brand new love songs.

WATCH: Dolly Parton On Her Looks, Wealth and Life Out of the Spotlight 

"This tour is called Dolly Pure & Simple, and I thought, 'Well, I need an album to go with that' and I didn't have time to do an album," she explained. "I just sat down one night and I started to write the song 'Pure & Simple.' I thought, 'That would make a beautiful love song. A simple country song.'

"So I wrote it and it really was pretty!" she continued. "Then I wrote another one, and another one, and it turned out to be a love song album. It's all love songs! It really turned out really pretty and a lot of the songs are done real simple."

Pure & Simple with Dolly's Biggest Hits is a two-disc set, to be released this summer, including all new material as well as a compilation of the singer's biggest hits.

Back in 1990, ET was in the studio with Parton as she recorded her beloved holiday release, Home For Christmas, featuring all traditional classics. See how she got in the Christmas spirit (as only Dolly could!) while recording in 90-degree heat in the player below.