Broadway golden couple Andy Karl and Orfeh split after 23 years of marriage over his relationship with co-star

Next time Broadway superstar Orfeh tells her actor husband Andy Karl to break a leg, she just might mean it literally.

The theater world was shocked earlier this month to learn that the pair — both Tony nominees — had split after 23 years of marriage.

But Page Six hears there’s more to the story.

Karl had been away in Australia starring in an Antipodean production of the musical adaptation of “Groundhog Day.”

(Karl also played the role made famous by Bill Murray in two London runs of the show, as well as on Broadway.)

But it seems that the actor had been “going down under” in more ways than one during his travels — and had, er, struck up a friendship with his co-star, Aussie Elise McCann, who was appearing in the Andie McDowell role.

Great White Way insiders tell us that Orfeh went to Australia in February to visit Karl, where he “paraded her around Melbourne as if everything was fine.”

Then told her shortly before she was due to return to the US that he, 49, planned to leave Orfeh, 53, for McCann, 38.

“He seems to be having a major midlife crisis,” a source close to the former couple told us.

“It’s one thing to fall in love with someone when you’re out of your normal reality in Australia and you’re starring in a show. Let’s see how this [new] relationship goes when it’s their day-to-day reality.”

Meanwhile, we’re told that when Karl posted a statement online announcing the split on May 14, he signed Orfeh’s name to it — but didn’t tell the “Legally Blonde” star about the post, let alone get her OK.

It reads: “After 23 years of a wonderful loving relationship, both onstage and off, we have made the decision to separate.”

It added, “Keeping a marriage strong can be challenging, especially when working on opposite sides of the world, but we remain committed to building a strong future, whether together or apart.”

Reps for Orfeh and Karl (they share a publicist) and McGann didn’t get back to us.