John Lithgow and His Wife of 43 Years Try to Follow This Rule When He’s Away on Location Filming (Exclusive)

John Lithgow and wife Mary Yeager have learned to turn the actor’s work trips into vacations.

Now that Yeager is retired from her job at UCLA, where she was a professor of business and economic history for decades, she’s freer to join her husband, 79, when he flies abroad to film.

“We've worked out this great system whereby she arrives to visit in all these exotic locations when I have only about two weeks left,” Lithgow, who recently shot his new movie Conclave in Italy, tells PEOPLE.

“By that time, I sort of know what I'm doing and I'm no longer a nervous wreck. And then at the end of the job we go off on holiday somewhere,” continues the six-time Emmy winner, who has won trophies for his work on Third Rock from the Sun, Dexter, The Crown and more. “It’s been completely wonderful.”

In recent months, Lithgow has been living in London while performing in Giant, a play that explores the antisemitism of Charlie and the Chocolate Factory author Roald Dahl. “It’s an incredible play,” says Lithgow.

The experience was made even more incredible by those who flew in: The father of three saw his daughter, Phoebe, who visited, and Mary has been able to join him “for the whole time.” (His run in Giant ends in mid-November.)

Lithgow and Yeager met in 1980 when the two — who were both married previously — were set up by a mutual friend. “She knew of our lunch date, but nobody had told me. There I was, sweaty, in borrowed tennis gear. She looked a picture. It was love at first sight,” Lithgow recently told The Guardian.

“Professors and actors are not supposed to marry. Our lives are so incompatible,” added Lithgow, who nevertheless wed Yeager in 1981.

They settled in Los Angeles for Yeager’s job, but work often took Lithgow away. It still does. “I’m going off to do fantastic things with fabulous new friends. It’s exhilarating and gives me life,” he told The Guardian. “But there are stretches where we’re apart, and it’s hard.”

For his new movie Conclave — a tense drama about the Cardinals who must elect a new Supreme Pontiff when the pope dies — Lithgow spent two months in Rome, exploring the city with costars Stanley Tucci and Ralph Fiennes. “It made you feel like a total nobody to walk down the streets of Rome with Stanley,” Lithgow says of Tucci, whose food and travel series, Searching for Italy, aired on CNN.

“Ralph and I felt like extras in Gandhi — absolutely no attention was paid! So you just had to swallow that bitter pill,” he says.

Conclave is in theaters Friday, Oct. 25.