Kate Middleton's heartbreak after huge William decision on key day for her

Nowadays, Kate Middleton, Princess of Wales , loves sharing her birthday with her nearest and dearest.

She spends her birthdays with her children Prince George, and Princess Charlotte , and mischievous young Prince Louis as well as her husband Prince William. Gone are the days when Kate could be found on a night out with Pippa Middleton, her sister.

However, the Princess of Wales suffered a major heartbreak on her 27th birthday when she had a tear-jerking send-off with her now-husband Prince William after she made a decision that reportedly “crushed” her.

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Despite being an item since their University days at St Andrew’s Kate was still waiting for the question to be popped. At one point during their relationship, Kate was labeled “Waity Kate,” by the media. In 2008, rumors were swirling around that William would finally pop the questions and was on the verge of getting down on one knee when it was announced that he’d signed up with the RAF. This news was out of the blue for both Kate and the royal family.

Having done a stint with each Armed Forces branch, William faced a crossroads - head back to the Household Cavalry or give up his military tenure to start on his regal responsibilities. Choosing the RAF meant a precious bit of extra time and liberty before diving into full-time Royal duties - a taste of independence neither his grandmother or father ever had, the Mirror previously reported.

Kate’s expectations of marrying Prince William and beginning her role as part of the royal family were dashed. In her book, "Kate: The Future Queen," Royal commentator Katie Nicholl wrote: "With that single decision, Kate 's life was turned upside down. She had expected a proposal once William had completed his military training but instead she was forced to accept that there would be no engagement any time soon. Kate would have to wait even longer."

Prince William's new role entailed 18 months of rigorous training in Shropshire, followed by a two-year stint at an undisclosed UK location. Nicholl writes: "Was Kate prepared to join him? She supported his desires and ambitions, but privately she was crushed. William was asking her [Kate] to be an army wife - without the nuptials. Her frustration was understandable."

As Kate's birthday approached, it marked the beginning of a new chapter in the couple’s life. Katie notes Kate struggled more as peers were settling down, leaving her feeling left out. Katie writes: "For Kate, it was a step backwards. It seemed that everyone was getting married except for her. As she neared her 27th birthday, Kate's plan to be married with children by the time she was 30 was looking increasingly unlikely."

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Katie also mentioned that not only Kate was concerned. Carole Middleton, her mother, was becoming "jittery" too. Yet, the couple persevered, with William often driving the 130 miles to Bucklebury to visit Kate. At the end of 2010, William cemented their relationship by proposing, though they kept the engagement under wraps until November 20 the following month. The duo sealed their union in an opulent Royal ceremony at Westminster Abbey in April 2011.