Al Pacino was perviously in a relationship with Diane Keaton (Image: Getty)

Al Pacino reportedly regrets never marrying Diane Keaton, following her de3ath Saturday in California.

Keaton and Pacino’s romantic history stretched over 16 years, beginning after they co-starred in The Godfather and other films.

Their relationship started in 1974 and ended in 1990 after Keaton asked him to marry her, according to a friend of the actor.

“He will forever regret he didn’t make his move when he had the chance,” a source close to Pacino told the Daily Mail.

“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.”

Diane Keaton passed away at 79 (Image: Getty)

The source said Pacino still refers to Keaton as “an amazing woman,” and acknowledged she was “the love of his life.”

Despite living near each other in Beverly Hills, the two reportedly had no contact for years. The friend said they “never spoke again.”

“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.’”

Keaton publicly addressed the end of their relationship in a 2017 Sunday Times interview.

“I didn’t even want him to propose. I just thought maybe he would marry me, eventually,” she said.

“I thought, ‘Don’t even propose – let’s just do it.’ But that never happened, and that is a blessing for both of us. It would have been a nightmare for him.”

She said they were mismatched from the start.

“We’re very eccentric, he needed a woman that was going to take care of him, I needed a man who would take care of me,” she said. “It was just very important that we left each other alone, said goodbye. But it wasn’t my choice.”