Russell Crowe has been crying the blues over ex-lover Meg Ryan, The National ENQUIRER has learned.

The Oscar-winning “Gladiator” hunk, 50, is finalizing his divorce from Aussie actress Danielle Spencer, 43, the mother of his two young sons.

But he’s telling pals that he should never have let the 52-year-old “When Harry Met Sally…” bombshell slip through his fingers. The pair had a steamy affair in 2000 after meeting on the set of their action film “Proof of Life.”

“Russell is getting all sentimental about Meg and what a passionate relationship they had,” an insider told The ENQUIRER. “He’s now wondering about where he went wrong.

“While he adores Danielle and the time they spent together, a big part of Russell is wondering why he didn’t seize the moment with Meg when he had the chance.”

The former couple’s romance exploded in acrimony after it emerged Meg was cheating on her then-husband of nine years, actor Dennis Quaid, who in turn was slammed by Meg for being unfaithful to her during the marriage.

In a 2008 blockbuster tell-all, the “Sleepless in Seattle” star confessed to Oprah Winfrey that she was “crazy” about Russell, but chose to end the relationship because she couldn’t cope with the spotlight.

The actor went on to marry blonde beauty Danielle in 2003, but they split after nine years.

Meanwhile, Meg has found love with rocker John Mellencamp, 62, and the two live together in New York City.

A second insider tells The ENQUIRER, “If the pretty star wasn’t hooked up, Russell would be with her in a flash.

“He says they connected on a level he’s never had with anyone, and their sexual compatibility was off the charts.”

The insider added: “Russell would do anything to have a second chance with Meg. But she’s moved on – and she isn’t the type to turn back time.”