Shania Twain and Robert "Mutt" Lange's private matter just became public fodder.

Just days after the duo announced their separation with nary an explanation, calling it a "private matter," comes a report that a third party was involved in their break.

Citing several sources close to the couple, People reports the record producer was involved—and continues to be involved—with the duo's longtime secretary and manager of their Switzerland home, the also-married Marie-Anne Thiébaud.

While the famously reclusive Lange initially called his split from Twain "unfortunate" and the result of "growing apart" after 14 years of marriage, he's wasting no time in lashing out at the magazine story, denying any semblance of impropriety.

"It's absolutely not the reason [for the separation]," he told People. "It's not true."

Twain, 42, and Lange, 59, have one child together, 6-year-old Eja D'Angelo.