What Prince William’s Birthday Tribute to Kate Middleton Reveals About How Her Cancer Diagnosis Has Affected Their Relationship

If anyone needed to kick 2025 off with a reason to celebrate, it was Kate Middleton, who spent most of 2024 out of the public eye while undergoing treatment for cancer.

So, when Kate turned 43 on Thursday, Jan. 9, it wasn't surprising that royal Instagram (and royal TikTok and royal Twitter/X) flooded with posts in honor of the Princess of Wales. What was a little surprising, however, was that her husband, Prince William, was one of the people who personally posted a birthday message for her on social media.

"To the most incredible wife and mother. The strength you’ve shown over the last year has been remarkable. George, Charlotte, Louis and I are so proud of you. Happy Birthday, Catherine. We love you," he wrote in a caption signed "W," along with a previously-unreleased picture of Kate.

As stunning as the black and white portrait (which was taken by royal photographer Matt Porteous, in Windsor, last summer, according to the Daily Mail) is, however, not even a beautiful, previously-unseen picture can pull focus from Will's personal message in the post's caption.

The mere existence of the public birthday tribute from William is significant. Some years, the Prince and Princess of Wales' official social media accounts haven't acknowledged Kate's birthday at all, and when they have shared posts to mark the occasion, the posts have been more formal than personal—like in 2022, when the couple's official Instagram account commemorated her 40th birthday by debuting her new National Portrait Gallery portraits.

Even though it was brief, Will's personal birthday tribute for Kate spoke volumes about the state of the couple's relationship following her cancer treatment, according to royal expert Hugo Vickers, who unpacked the significance of the post.

According to The Sun, Vickers believes the message could "signal a new openness from the royal family since [Kate's] cancer treatment."

"This message of admiration from Prince William is very heartfelt and very special and I think that we're all very pleased that she's gradually getting better," Vickers explained.

The royal author honed in on one word in the message as being particularly meaningful: Strength.

"William mentioned the word strength, and I think that is one of her quiet qualities," Hugo added. "It's sort of an inner strength that she has a confidence and something which is not in any way overt or explicit. But it's just there, and I think that's one of the things that we admire about her, her resilience and her determination."

While Kate has clearly demonstrated a great deal of strength in the past year amid her cancer treatment, Vickers also pointed out the impact her health journey has had on William.

"I've got sympathy for Prince William, because he must have had a pretty difficult year himself, and he has indeed said so, and in fact, he said, it was the most difficult year of his life," Vickers explained. "Having a wife who is not well, and three small children, and all the other responsibilities that come with his position in life, he's got a lot on his shoulders, and I think he's handled it very well."

In its report, The Sun noted that Vickers "explained the tribute demonstrates solidarity in marriage, teamwork, and the importance of family and unity" and "believes the post itself emphasi[z]es how the couple are strong together."

The royal expert concluded his analysis of the post with a kind of tribute of his own to Kate, calling her "the great star of the Royal Family" and "the great hope of the future" before declaring, "One day she'll make a wonderful queen."