Shania Twain and her music producer husband are separating after 14 years of marriage due to his relationship with another woman, several sources told People magazine.

Twain's estranged husband, Robert "Mutt" Lange, told People the split was "an unfortunate thing." He added, "It's literally just a growing apart, that's all."

But sources close to the situation told People that Marie Ann Thiébaud, a longtime secretary and manager of the couple‚Äôs chateau in Switzerland, was at the center of the break-up.

"Mutt and Marie Ann left their spouses for each other and are still in a relationship," one source told People.

Lange denied the claims to the magazine.

"It's absolutely not the reason [for the separation]," the famously reclusive producer told People when asked about the alleged affair. He also denied that he was in a romantic relationship with Thiébaud: "I'm not, no," he said. "It's not true."

Twain, 42, and Lange, 59, married in 1993. They have a 6-year-old son, Eja (pronounced "Asia") D'Angelo.

An insider told People that Twain is "devastated. This came out of left field ... She loved him."

Twain is best known for her hits "Man! I Feel Like A Woman!" and "You're Still the One." Lange produced three of Twain's albums: 1995's "The Woman in Me," 1997's "Come on Over" and 2002's "Up!"

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