The party took place, but Mary was pensive and not the usual carefree and easygoing hostess everyone was used to.

Her thoughts were clearly elsewhere - she couldn't stop thinking about Copenhagen 1015K.

Not only is this the address of the palace, it's also the title of the cause of her seething rage - a new bombshell book that claims Mary's marriage is in serious danger and she's not the love of Prince Frederik's life.

Mary learnt about the sensational book in June. A palace source says she was 'terribly upset' and threw it down, 'disgusted and burning with rage' after reading a few pages. But the 'revelations' have undermined the princess' confidence, and she's under obvious strain. In Romania recently, Mary forced a smile while Frederik grinned, neither of them looking at the camera or at each other.

The book claims Mary married into a dysfunctional family and is unable to cope, so she's decided to lock herself away in the palace. It goes further and suggests that the fairytale is over for the couple and that their marriage is in serious trouble. 'The most hurtful thing in the book is the assertion that Mary is not the love of Frederik's life after all. 'She's fuming about this. She's the mother of his two children and the woman he married, not just dated,' a friend of the princess says.

The book claims that the love of Frederik's life is former Danish underwear model Katja Storkholm, and that Mary is also feverishly jealous of another woman who enjoyed a passionate and significant romance with Frederik, fashion design student Bettina Odum.The author says Frederik was dating Bettina when he met Mary, and had told his mother he wanted to marry her but she refused. Weeks before he left for the Sydney Olympics in 2000, he and Bettina holidayed on the Mediterranean. She was snapped topless, which caused a huge scandal for the royals. Frederik met Mary, but he was again seen with Bettina in the New Year of 2001, partying up a storm in Copenhagen and holidaying in Northern Denmark while Mary was all alone in Sydney. Then, on March 15, Bettina announced that her relationship with Frederik was over.

'It was my decision to end it, but I'm not an unhappy girl now,' she said at the time. 'What happened was best for both of us.'
But underneath it all, Bettina was fuming she'd been forced to end it with the prince because he'd started seeing someone else. Bettina is now a happily married mum, yet the book's author, Trine Villemann maintains she's a presence in Frederik's life and is a 'Camilla figure' to him.

Another woman who featured strongly in Frederik's romantic past was his stunning underwear-model lover Katja. The book suggests that Frederik desperately wanted to make her his wife, but that Queen Margrethe forbade it. The book also claims Frederik still holds a torch for Katja, who's now married.

But Trine says Mary's still extremely jealous of all Frederik's former girlfriends. 'He has beautiful, intelligent, strong exes who he's still in touch with,' she says. 'Mary came across the world to be with him, so why can't he stop seeing them? The happy girl from Hobart has gone, and now we have this emaciated princess wearing designer clothes.'

When Frederik was asked why he fell in love with Mary, he said it was because of her elegance and frankness. He said they were on the same wavelength most of the time, but they could also amicably disagree. Mary said she fell for Frederik because: 'He's so intelligent, gentle and funny.'

The palace dismisses the book as lies. Courtiers have refused to comment publicly, but one says: 'These claims are utter rubbish - the prince and princess have just had their second child and are happier than ever.'

Is Mary destined for heart ache like Diana or is her marriage to Prince Frederick rock solid?