For nearly four decades, Tom Selleck has enjoyed something surprisingly rare for one of Hollywood’s biggest stars: a long marriage that has largely unfolded away from Hollywood.

Selleck married British actress and dancer Jillie Mack on August 7, 1987, after meeting her while she was appearing in Cats in London. Even their wedding reflected what would become a defining rule of their relationship — keep what matters most private. The ceremony near Lake Tahoe was so closely guarded that news of the marriage didn’t become public until weeks later.

But privacy was only part of the story.

At the height of his Magnum, P.I. fame, Selleck was working an exhausting schedule. Eventually, he made a decision few stars at the top of their careers would have made: he stepped away from the series and put more of his attention toward building a family life.

“I quit Magnum to have a family,” Selleck later explained. He and Jillie settled on a ranch in California, where they raised their daughter, Hannah, far from the everyday Hollywood spotlight. Selleck has described time with his family as his first priority and said that taking time away from work was good for his marriage.

Perhaps the most revealing explanation came years later when Selleck talked about how his relationship with Jillie had changed with time.

Rather than chasing the excitement of their early years together, he said their love had become “deeper” and “simpler.” He described the two of them as true partners who knew they loved each other and maintained lives and interests of their own.

That may be the real secret behind the Sellecks’ longevity.

They didn’t turn their marriage into part of Tom’s celebrity brand. They protected their home life, made decisions together and created a world where being a husband and father could exist separately from being a television star.

Nearly 40 years after that secret Lake Tahoe wedding, Tom Selleck and Jillie Mack remain together.

For a man who spent decades playing unforgettable characters, one of Selleck’s most enduring accomplishments may simply be the life he chose when the cameras weren’t rolling.