BEN Affleck’s night of glory – when his movie “Argo” won the Oscar for Best Picture – turned ugly as the actor/director got into a very public dust-up with his actress wife Jennifer Garner.

The ENQUIRER has a shocking photo of the celebrity couple arguing bitterly during an after-party – and in our latest issue we reveal the stunning reason why their marriage has been pushed to the brink!

Ironically, Ben’s crowning moment sparked the fight. During his Academy Award acceptance speech, the hunk made his marriage sound like a lot of work!

“I want to thank my wife, I want to thank you for working on our marriage for ten Christmases,” he said. “…It is work, but it’s the best kind of work, and there’s no one I’d rather work with.”

Jennifer smiled for the cameras but then pulled her head back and grimaced.

Later on, during a bash at the Sunset Tower Hotel, a source says Jennifer read Ben the riot act, hissing: “What do you mean our marriage is work?”

But the stars — parents of three young kids — have been struggling for years to keep their union intact, say sources. And the latest issue of The ENQUIRER rips the lid off the REAL reason behind their marriage woes.

It’s one story you won’t want to miss!