David McCallum & Wife Made It to 56, Days before He Died — Their Love Didn’t Break Even When They Lived Apart for Years

• David McCallum had a photo from the day he met his second wife.
• The actor had a rule that contributed to their happy marriage.
• David and Katherine Carpenter McCallum were "two halves of a whole."

The late David McCallum had an unconventional marriage by some standards. For a great part of his union with his wife of 56 years, Katherine Carpenter, they mostly lived on opposite coasts from each other.

For ten months out of the year, McCallum filmed "NCIS" in Los Angeles, while Carpenter, a former model, was based in New York City. She worked at one of the oldest design firms in the country as an interior designer.

The couple constantly kept in touch through the phone and spent major holidays such as Thanksgiving together. The actor jetted between the coasts, but NYC was his home base.

"My wife, at this point, would like to become two people—one that would be here in California and one there in New York, he admitted in 2016, 13 years into the arrangement, "and we both feel that way."

In mid-2015, McCallum recalled the day he met Carpenter in an upload featuring two images taken 50 years apart. The day they met was captured in black and white and what looked like a still from the spy television series that made him an international star, where a youthful McCallum and Carpenter are mid-dash in front of the Flatiron Building in Manhattan; in the foreground, a man lies on the sidewalk.

The image 50 years later was a selfie of the two taken a week before the post, featuring the same background as the one in black and white.

Decades into their marriage, the pair could still dance "for hours," according to McCallum, who revealed in a post in August 2015 that during the 80th birthday bash of "NCIS" creator Don Bellisario, he and his wife spent hours on the dance floor. A blurry photo of them showed them tearing up the dance floor to what the caption identified as Big Band classics from the 1940s.

Their wedding anniversaries were also featured annually on his social media platform. On September 16, 2016, he shared a photo with Carpenter on the subway. She smiles broadly with her arm around his shoulders. The next year, he shared a photo from a dinner celebrating 50 years of marriage.

"The Man From U.N.C.L.E." actor was previously married to the actress Jill Ireland, with whom he adopted three boys. She left him for his "The Great Escape" co-star Charles Bronson. One of their sons died from a drug overdose in 1989.

David McCallum Ensured His Wife Had Everything She Wanted in Life

When asked in an interview what the secret to a happy marriage was, McCallum revealed that he and his wife approach their relationship "instinctively." However, as a rule, he believed, "You should find out what the other person wants in life and make sure they get it."

In another interview, he repeated this sentiment: "The best thing about a marriage is you find out what the other person wants and make damned sure they get it."

"Katherine and I are two halves of a whole," the Scotsman said. "We work well together, and when problems come along, we solve them."

The couple had two children, a son and daughter, and many grandchildren, of which the cheeky ones called him "grand-ducky." David McCallum died at 90 from natural causes in New York Presbyterian Hospital, surrounded by family.