Shania Twain's 'unfaithful' husband blamed for marriage break-up after 14 years

Shania Twain broke up with her husband after 14 years of marriage because of his relationship with another woman, it is claimed.

The country music star announced her breakup from music producer Robert Lange earlier this month.

Lange described the split 'an unfortunate thing. 'It's literally just a growing apart, that's all," he said at the time.

Now, however, America's respected People magazine  says a third party was involved, namely Marie-Anne Thiébaud, a longtime secretary and manager of the couple’s chateau in Switzerland.

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

However Lange has denied the claims saying. 'It's absolutely not the reason .'

He also denied that he was in a romantic relationship with Thiébaud: 'I'm not, no,' he said. 'It's not true.' Thiébaud could not be reached for comment.

Twain, 42, and Lange, 59, married in 1993. They have a six-year-old son, Eja D'Angelo.

An insider says the You're Still The One singer is 'devastated', adding: 'This came out of left field ... She loved him.'

Another source close to Twain said that the Canadian-born star was coping with the help of  'a very close-knit group of family and friends.'

Shania Twain with husband Robert 'Mutt' Lange in happier times