Hugh Jackman allegedly stepped out on his marriage to Deborra-Lee Furness with his “The Music Man” co-star Sutton Foster.

Sources claimed to US Weekly on Tuesday that Jackman, 56, had “an affair” with Foster, 49, while he was still married to Furness, 68.

“Sutton and Hugh’s relationship is the reason Hugh and Deb got divorced,” a source close to Foster told the outlet.

They added, “A lot of people on Broadway knew, and we kept it quiet because both of them are so nice and great people. Everyone respected their privacy. But there was an affair and overlap.”

The insider also claimed Jackman and Foster are together at the moment. “They are really happy now,” they said.

The Post has reached out to reps for Jackman and Foster for comment.

Jackman announced he was separating from his wife of 27 years in September 2023. The former couple share adopted children Oscar, 24, and Ava, 19.

Foster, meanwhile, filed for divorce from her husband of 10 years, “Ocean’s Eleven” screenwriter Ted Griffin, last month — just as news broke about Jackman and Foster’s alleged secret romance. Foster shares an adopted daughter, Emily, 7, with Griffin, 53.

Sutton Foster, Ted Griffin at a Broadway show in February 2019.

Jackman and Foster were co-stars in the Broadway revival of “The Music Man” that started previews in December 2021 and ran through January 2023.

According to an US Weekly source, Furness “was blindsided” when she learned of Jackman’s relationship with Foster.

Sutton Foster and Hugh Jackman at the 2022 Tony Awards.

“It was apparently Broadway’s worst-kept secret, and Deborra-Lee was the last to know,” the industry source claimed, adding that Jackman “didn’t own up” to his alleged affair with the “Younger” actress.

A friend to the former couple said that Furness is devastated in the wake of the scandal.

“I think many people were shocked [Hugh] could do this to her, especially as she’s the mother of his children, and they’ve navigated three decades of life together,” said the friend. “A little respect may have been in order.”

Meanwhile, a theater source claimed Jackman and Foster are a couple “but don’t live together because of their kids.” The insider added, “But Sutton has told people on Broadway about the relationship. Everyone [there] has known about this for a long time.”

Jackman and Foster were very open about how they formed a tight relationship when they were Broadway co-stars.

On “Late Night With Seth Meyers” in May 2022, Foster said she was “having the time of my life” working with the “Deadpool & Wolverine” star.

“I’ve watched everything she’s done. It’s amazing,” Jackman gushed about Foster in the interview.

On “Live with Kelly and Ryan” in July 2022, Foster said the pair hung out in her dressing room before every “The Music Man” show.

“It’s such a wonderful thing,” Foster added about her bond with Jackman. “That’s been one of the best parts of the whole thing, that I’ve made this wonderful new friend.”

Hugh Jackman’s ex-wife Deborra-Lee Furness subtly reacts to his alleged affair with Sutton Foster

The 56-year-old was married to ex-wife Deborra-Lee Furness for 27 years before the two announced they were divorcing. Rumors have swirled over the past few months that Jackman possibly stepped out of his marriage to Furness, 68, with his “The Music Man” co-star, 49.

Now, the Australian actress has seemingly reacted to news of the “Deadpool & Wolverine” star’s relationship with Foster.

Furness “liked” a post from her private Instagram account of gossip blogger Tasha Lustig claiming that Jackman had “blindsided” Furness by sharing his relationship with Foster, per US Weekly on Wednesday.

The producer’s friend, British media personality Amanda de Cadenet, also weighed in on the allegations, writing in a comment last month, “You are on point with this one. My beloved friend Deb is about to have her glow up any moment fyi!”

The Post has reached out to reps for Jackman, Furness and Foster for comment.

Meanwhile, sources claimed to the outlet on Tuesday that Jackman did have “an affair” with Foster.

“Sutton and Hugh’s relationship is the reason Hugh and Deb got divorced,” the insider, who is close to Foster, said.

“A lot of people on Broadway knew, and we kept it quiet because both of them are so nice and great people. Everyone respected their privacy. But there was an affair and overlap.”

The source also claimed Jackman and Foster are together at the moment, adding, “They are really happy now.”

Furness reportedly had “suspicions” about her longtime husband working with the actress on Broadway.

Jackman and Foster appeared together in “The Music Man,” which ran on the Great White Way from December 2021 to January 2023.

Nine months later, Jackman and Furness announced the end of their 27-year marriage.

“Deborra-Lee had her suspicions when Hugh started working with Sutton,” a source told the Daily Mail earlier this month. “Their relationship is not a secret to her.”

Earlier this week, Page Six reported that Foster filed for divorce from her husband of 10 years, Ted Griffin, with sources telling the outlet that she and Jackman are now officially an item.

“They are 100% together and are in love and want to spend the rest of their lives together,” one insider stated. “They go out of their way to hide it, but it’s common knowledge.”

Furness, who shares adopted children Oscar, 24, and Ava, 19, with Jackman, has yet to speak publicly about the end of her marriage to the “X-men” hunk — or rumors that he and Foster are dating.