EXCLUSIVE: Read Princess Diana's Uncensored Love Letters to Prince Charles — Written As She 'Tried Everything' to Woo Him Away From Mistress Camilla

When Princess Diana married then-Prince Charles, she was only 20 years old, and like any young bride, she hoped she and her new husband would enjoy a long, happy life together, RadarOnline.com can reveal. But when her 36-year-old husband turned out to be a cold fish, she didn't give up.

The beautiful royal poured her heart into ink, believing if she wrote the right words – if she expressed them beautifully enough – she could bridge the distance between them.

But for every letter sent, there was silence in return. Diana, young and full of hope, penned the tender, longing letters to her husband in the early years of their marriage. In them, she detailed her dreams for their future and whispered affections onto pages meant to rekindle the love she thought they once shared.

But Charles, preoccupied and emotionally distant, never wrote back.

"It's such a sad thing to say that he never loved her, and so he never returned the compliment. He wasn't romantic. He tried to be, but he didn't have a romantic bone in his body," said former royal butler Paul Burrell.

The groom, however, tried his best.

The night before the July 29, 1981, wedding, Diana received a special letter and a gift from her husband-to-be.

The late royal shared: "He sent me a very nice signet ring the night before to Clarence House, with the Prince of Wales feathers on and a very nice card that said, 'I'm so proud of you, and when you come up, I'll be there at the altar for you tomorrow... Just look 'em in the eye and knock 'em dead.'"

Though the gift and the letter were touching, and she was "so in love" with Charles, their marriage never stood a chance. He was already in love with Camilla Parker Bowles, whom he would marry in 2005, eight years after Diana's tragic death in a Paris car crash.

But the People's Princess was full of hope, which already started to ebb away on their honeymoon.

Princess Diana may have detailed her honeymoon to Charles as a "tremendous success" in a 1981 letter to her family's former housekeeper, but she later confessed the trip was a nightmare.

According to royal author Penny Junor – who wrote the biography The Duchess – Charles packed novels and art supplies for the couple's honeymoon, which saw them visit several destinations, including Tunisia, Algeria, Sicily, the Greek Islands, Egypt, and Scotland.

He had hoped they'd share the books and then discuss them in the evenings, but his new bride didn't want to discuss books during the honeymoon, she wanted to spend time with him.

Junor said: "She hated his wretched books and was offended that he might prefer to bury his head in one of them rather than sit and talk to her. She resented him sitting hours at his easel, too, and they had many blazing rows."

In fact, one day when Charles was painting on the deck of the Britannia, he went off to look for something. He came back to find that Diana had smashed his easel and art supplies to smithereens.

They also fought over the fact that Charles wore cufflinks Camilla had given him – two Cs entwined. Diana asked him: "Camilla gave you those, didn't she?"

He said: "Yes, so what's wrong? They're a present from a friend."

Diana later said: "And boy, did we have a row. Jealousy, total jealousy."

Many years later, a royal maid stumbled upon a forgotten bundle of these letters tucked inside an old writing desk at Kensington Palace. The intimate writings lay undiscovered for decades, only coming to light when palace staff moved furniture during a renovation.

The desperate letters are filled with the yearnings of a woman trapped in a loveless marriage.

A royal insider said: "She never stopped trying. She loved him so much, but he never gave her that love in return. It broke her."

The letters, never meant for the public eye, reveal the heartbreaking truth of Diana's marriage – a woman who loved deeply, but was left longing for a love that never truly came.

In the letters, Diana poured out the secrets of her lonely heart. One of them read: "I miss you. Even when you're beside me, I miss you. I won- der, do you ever feel the same? Or is it just me, lost in this love, trying to make sense of what we've become?

"I think about our wedding day and how I felt walking toward you – like I was stepping into a dream, a fairytale come true. But fairytales don't have quiet, lonely nights. They don't have the silence we sit in now."

In another she penned: "Sometimes I watch you when you don't realize it. You look away when I reach for your hand. You nod politely when I tell you I love you, but you never say it back. Do you? Do you love me? Or am I simply someone who walks beside you, plays the part of a princess while you dream of another? If there is even a part of your heart that belongs to me, please, tell me. I will wait for your reply."

Camilla and King Charles will celebrate their 20th anniversary on April 9. They're planning to spend their milestone anniversary on a royal tour of Italy and Vatican City, said insiders.

Ex-butler Burrell said: "It is astonishing to think that Charles and Camilla's wedding anniversary is 20 years this year. Charles made up for his lack of romance [with Diana] with Camilla. He's been married to Camilla longer than he was married to Diana. That is astonishing."