The Princess of Wales, previously known as Kate Middleton, marked her 44th birthday on January 9th. It’s believed that Kate spent the day joyfully with her husband, their three children, and close family, much like she has in previous years.

However, there’s one birthday that the princess might remember less fondly—her 27th.

Let’s delve into why that particular birthday wasn’t a cheerful occasion for her, following an unexpected move by Prince William.

William’s choice derailed Kate’s plans for where she thought she would be at 27

Royal expert Katie Nicholl detailed in her book, Kate: The Future Queen, how this choice by William affected Kate. Nicholl wrote, “With that single decision, Kate’s life was turned upside down. She had expected a proposal following William’s military training, but instead, she realized there would be no engagement soon. Kate faced an extended wait. Despite supporting his ambitions, she was privately devastated. William was essentially asking her to be an army partner without exchanging vows, and her frustration was completely justified.”

In her book, Kate: The Future Queen, royal commentator Katie Nicholl explained, “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. She supported his desires and ambitions, but privately, she was crushed. William was asking her to be an army wife — without the nuptials. Her frustration was understandable.”

Nicholl added, “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 thirty was looking increasingly unlikely.”

The prince and princess acknowledged some difficult times in their past

Of course, William did eventually propose. It happened when they were on a trip together in Kenya. They shared their happy news with the world a few weeks later in November 2010. The prince shared why he chose that location to ask Kate to marry him.

“Africa is definitely one of the places I go to. It does completely settle me down,” he said. “[Kate] understands what it means to me being in Africa, and my love of conservation. I didn’t really plan it that far in advance. I just knew I wanted it to feel comfortable where I did it.”

During their joint post-engagement interview, the two were also asked about some of the difficult times earlier in their relationship.

“We were both very young,” William said as he opened up about their first breakup. “It was at university, we were sort of both finding ourselves as such and being different characters and stuff, it was very much trying to find our own way and we were growing up.”

Kate chimed in, adding, “I think at the time I wasn’t very happy about it, but actually, it made me a stronger person.”