The shaky marriage of ANTONIO BANDERAS & MELANIE GRIFFITH took yet another hit when the dashing actor was spotted dining with a sexy mystery woman on the French Riviera.

“Working Girl” star Melanie, 56, was thousands of miles away in Los Angeles, and a source says she flipped out over photos of her husband’s cozy dinner date.

“Melanie saw the pictures, and she’s both furious and heartbroken,” a source told The ENQUIRER.

Antonio’s intimate dinner on May 17 came just weeks after The ENQUIRER reported that he’d walked out on Melanie to spend the Easter holidays in his native Spain.

What’s more, his under-the-radar evening at a restaurant in An­tibes came just three days after the 53-year-old movie hunk’s 18th wedding anniversary.

Antonio – who was in France to promote his film, “The Expendables 3,” at the Cannes Film Festival – greeted his dinner date with a warm hug and a kiss, then spent most of the evening with his arm draped over her chair.

“The two of them looked very cozy,” said the source.

Meanwhile, Melanie was spotted at Los Angeles International Airport that same day. She touched down af­ter a five-hour flight from New York’s JFK airport, wearing a sheer black top that exposed her bra and midriff.

As The ENQUIRER has reported, the couple’s marriage has been tested repeatedly.

Antonio re­portedly flirted with two exotic beauties at the 2012 Cannes Film Festival – after he was caught getting close to a young Melanie look-alike at a Cancun nightclub.

Melanie got even by flirting with hot “Hawaii Five-O” star Scott Caan.

And while Antonio was in Spain with his arm around the shoulder of pretty Spanish politician Susana Diaz, Melanie was spotted having lunch with a handsome young male friend in West Hollywood on April 9.

The couple has a daughter, 17-year-old Stella, and Antonio has supported booze- and drug-troubled Melanie during three trips to rehab.

“Melanie has done her best to keep Antonio interested in her, but their marriage has already been under a lot of pressure lately and this latest incident is certainly not going to help,” said the source. “It could push things over the edge.”

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