In the new issue of Closer Weekly, on newsstands now, Dolly Parton’s close friends and family open up about her unique, long-lasting and unconventional marriage to Carl Dean, revealing why time apart from each other actually makes their relationship stronger!

“They let each other be free to be the way they are,” Dolly’s sister, Stella Parton, tells Closer. “They are very unique but they complement each other.”

It’s one of the most successful marriages in show business, however, according to an insider, in 2015 Dolly was away from home as many as 165 days!

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Dolly in 1970.

“She does what he loves to do for part of the year,” Sam Haskell, Dolly’s friend for nearly 30 years, tells Closer. For the other part of the year, Dolly does what she loves to do, “which is her work,” reveals Sam. “She keeps her personal life and her professional life separate — and I think that is the secret to their marriage.”

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A friend reveals to the magazine that Dolly even keeps “a small cabin." "It’s like half a little chapel and half a work space. There’s no phone, and Carl never ventures in there — it’s Dolly’s space. She can spend hours out there, just strumming a guitar and working out songs. You can call it her happy space, but more accurately it’s her sane place to get away from all the craziness of her life," the friend said.

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Dolly in December 2015.

So many nights spent apart might spell disaster for another marriage, but Carl, who runs a paving company in Nashville, Tenn., understood Dolly’s big ideas from the moment they met, when she was just 18-years-old.

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“Theirs isn’t a traditional marriage, but it works for them," a friend tells Closer. “Carl’s attitude is, ‘You go do your thing and I’ll do mine… see you when you get home!’”

For more on Dolly Parton, pick up the latest issue of Closer Weekly, on newsstands now!