JEALOUSY ruined RUSSELL CROWE’s marriage to Aussie actress Danielle Spencer – but she stands to reap millions from their split!

The hotheaded Aussie, 48, never got over Danielle, 42, stepping out with her hunky partner on the Down Under version of “Dancing with the Stars” in late June, sources say.

“Russell’s ego couldn’t handle it,” said a source.

“In his mind, it was perfectly OK for him to spend time away from home – working, hitting the bars with his mates and carousing until all hours. But when Danielle was spotted out with another man, it was a totally different matter. Russell hit the roof!”

A divorce is sure to hit Crowe hard in the wallet.

His real estate holdings alone are estimated at $50 million, including a $14 million penthouse in Sydney, along with a $10 million mansion and a big chunk of farmland in Australia. Danielle could walk away with up to $25 million and another $3 million apiece going to their sons Charles, 8, and Tennyson, 6.

The Oscar-winning “Gladi­ator” star met Danielle, also a singer/songwriter, in 1990 when they co-starred in “The Crossing,” an Australian movie.

They finally wed in April 2003 in a chapel on Crowe’s 750-acre ranch in New South Wales.

But their relationship crumbled after Danielle was spotted with her boyishly handsome “Dancing” partner Damian Whitewood on June 21 at a casino lounge in Sydney. The “date” sparked rumors of marriage trouble, which Crowe tried to scuttle by planting a passionate kiss on Danielle when she arrived in L.A. with their boys a few days later.

“But it was all for show,” said a source. “By that time, theirs was a marriage in name only. Russell had buried himself in his work, doing a number of films back to back, and Danielle rarely saw him.”

Crowe has six films due out over the next year, including “Man of Steel” and “Noah.”

Ironically, it was shortly before he wed Danielle that Crowe was caught up in a scandalous affair with his married “Proof of Life” co-star Meg Ryan.

The source said: “Dani­elle has long suspected that Russell has had flings while he’s working, but she turned a blind eye.

“But when she was out with someone else – no matter how platonic the situation was – Russell boiled over. And THAT was it!”