The heartbreaking passing of Diane Keaton has left renowned actor Al Pacino reflecting deeply on his most significant regret: not marrying her when he had the chance.

Keaton, who passed away at 79 on Saturday, was the enduring love of Pacino’s life. Their on-and-off relationship spanned from 1971 to 1987.

Despite their deep connection, the 85-year-old star of “Serpico” never took the step of proposing to Keaton.

Eventually, after years of being together, Keaton presented Pacino with a clear choice: marry her or part ways.

Faced with the ultimatum, the “Godfather” actor chose to walk away.

Diane Keaton’s sudden death has left her former co-star Al Pacino dwelling on his biggest regret: that he didn’t marry her when he could have (Pictured: The Hollywood stars in The Godfather)

Keaton (pictured May 2019) died on Saturday. Her cause of death has not yet been announced

‘Looking back, Al admits the love of his life was Diane who he’s always called, “an amazing woman”,’ a friend of the actor told the Daily Mail.

‘I know he will forever regret he didn’t make his move when he had the chance.

‘For years after he and Diane split, Al used to say, “if it’s meant to be, it’s never too late for a do-over”. But sadly, now it is.’

The source said while Pacino romanced a bevy of beauties, his kids have always been the most important thing in his life.

‘Al adores all his kids,’ the source said. ‘And although he preferred living in New York, he also purchased a home in Los Angeles just so he could spend more time on the West Coast with his children who lived there.

‘Though he and Diane both lived in Beverly Hills, only a few miles from each other for years, they never spoke,’ the insider revealed. 

‘I once asked him why, and he told me, “There’s no need to talk with each other. We said everything that needed to be said at the time”.’

Pacino and Keaton met on the set of the hit film The Godfather where he played Michael Corleone and she was his second wife, Kay.

Now the world will see if he will attend her funeral or memorial service.

No cause of death has been announced but Keaton, who was regularly seen out and about in LA, disappeared from the site a few months ago.

One neighbor told the Daily Mail he would regularly see her walking her dog Emma.

Pacino and Keaton met on the set of The Godfather where he played Michael Corleone and she was his second wife, Kay

‘But I hadn’t seen her in months,’ the neighbor said. ‘Now I wonder if she may have been ill for a while.’

The Annie Hall Oscar-winner was always open about her battle with skin cancer when she was much younger. 

Her signature look of hats, turtlenecks and gloves was more for sun protection than a quirky style of fashion.

Like Pacino, Keaton never married, but she often admitted privately that she would have tied the knot with him if he had asked. 

The late actress also used to say marriage was never something high on her bucket list.

‘Diane’s parents were together, but her father was always away on business,’ said another source. 

‘So, he might as well not have been there at all. She loved her mother, who managed the home and raised her four children on her own, and Diane admired her strength and independence.’

Keaton, whose movies included First Wives Club, Reds, Looking for Mr. Goodbar and a whole slew of collaborations with Woody Allen, also dated actor Warren Beatty. 

The stars had an on and off again relationship for nearly two decades, but when Keaton gave Pacino (pictured September 2025) an ultimatum to marry her or walk away, he headed for the nearest exit

She crushed on him for years but their relationship was short-lived.

She also shared a close relationship with Allen for two decades, but it wasn’t the same kind of relationship she shared with Pacino. 

Still, Allen was said to be ‘extremely distraught’ over her death.

‘There was something about Al that reminded her of a lost orphan in need of love,’ shared the source. ‘And she felt sure he would never try and take her independence, because he needed her to be strong.’ 

Ironically Keaton had her own regrets. 

‘Al was charming, hilarious and a non-stop talker,’ she said recently. ‘And oh, he was gorgeous! I was mad for him, and I worked hard on that one, but I guess I went about it in a not so perfect way.’

‘Diane could definitely have seen herself marrying Al, and them having kids together,’ added her friend.

‘But after years of on and off romance, she felt the time to marry was now or never. And she eventually told him: “Marry me or else!”

‘To her surprise, he walked away, insisting no woman was going to push him into doing something he wasn’t ready to do. And true to his word, he moved on.’

Keaton is seen in her final Instagram photo smiling as she cuddled up with her dog 

Like Keaton, Pacino has had several serious relationships. He has a 36-year-old daughter, Julie, with one time partner Jan Tarrant, and 24-year-old twins Anton and Olivia with actress Beverly D’Angelo.

Two years ago, he had a son with then-girlfriend Noor Alfallah.

Keaton was childless for years until she entered her 50s and adopted her 27-year-old daughter Dexter, and her 22-year-old son Duke, who now survive her.

According to the source, Pacino has never been a person who does what others tell him. 

‘Al has never been one to be pinned against the wall on anything,’ they told the Daily Mail.

‘He has always marched to his own drummer, and no one tells him what to do. His parents divorced when he was two, and growing up without a father in the house was difficult.

‘And while he went on to have four kids with three different women, he never walked any of them down the aisle.’