Robert Wagner, 96, has attributed the enduring success of his marriage to actress Jill St. John, 86, to maintaining a deep sense of interest in one another.

'Being interested in life and in your relationship,' Wagner told Entertainment Weekly. 'I mean, I find Jill very interesting, a very interesting person. I think interest is important in a relationship.'

The couple, who have been married since 1990, first met as young contract players at 20th Century Fox in the late 1950s. Their careers briefly intersected in 1967 when St. John appeared in Wagner's film 'Banning' and they co-starred in the television movie 'How I Spent My Summer Vacation.'

Following the mysterious drowning death of Wagner's wife, Natalie Wood, on Thanksgiving weekend in 1981, St. John sent Wagner a sympathy card. They reconnected in early 1982 and began dating on Valentine's Day that year.

In 2007, the couple relocated from Los Angeles to Aspen, Colorado, where they have resided full-time. Wagner frequently marks their anniversaries and St. John's birthdays with affectionate tributes on social media. For their 36th anniversary in April, he posted a photo of himself kissing St. John's cheek, captioning it, '36 years of love and laughter with my beautiful Jill. Happy Anniversary, my love.'

Wagner also continues to share memories and celebrate milestones with Wood's family. Earlier this month, he posted a photo with Wood's daughter, Natasha Gregson Wagner, for her 56th birthday. Wagner helped raise Natasha after Wood's death and legally adopted her, referring to her affectionately as his 'daughter.' He has also commemorated past wedding anniversaries with Wood on social media.

Natalie Wood's death in November 1981 occurred during a Thanksgiving weekend boat trip on the yacht Splendour with Wagner and Christopher Walken. Her body was discovered the following morning. The initial ruling of accidental drowning was amended to 'undetermined' after the captain of the boat later stated he had heard an argument between Wood and Wagner before she disappeared. Wagner was named a person of interest in 2018 but was cleared of criminal involvement due to insufficient evidence four years later.