Prince Charles and Camilla Parker Bowles's relationship on the rocks?

As the couple marked their third wedding anniversary last week, friends have revealed that Charles and Camilla are constantly at each other's throats, as they struggle to make their marriage work.

The Duchess of Cornwall was noticeably absent when Charles accompanied Prince William and Kate Middleton on a skiing trip to the royals' favorite ski resort in the Swiss Alps during the last week of March.

Sources have told the UK's Mail On Sunday newspaper that the situation has become so tenuous that even the presence of Palace staff is not enough to cool down the couple's bitter fighting.

"The rows have been escalating over the past three months," a Palace source told the paper. "The staff is getting tired of it, because you can't help but hear the shouting ... as you can imagine, it's hugely embarrassing when that happens."

"She is happy to spend time at Ray Mill," a close friend told the paper. "Charles will never go down there to comfort her. He just sits it out."