Prince William is feeling the weight of responsibility as his father, King Charles III, and his wife, Kate Middleton, undergo cancer treatment, according to royal experts.

The British royal family has been left strained after both the current monarch and the future queen were diagnosed with cancer earlier this year.

Royal biographer Christopher Andersen told Fox News Digital that "now everything rests on Prince William's shoulders" following the "unprecedented one-two punch" of King Charles' and Princess Kate's cancer diagnoses.

"Having lost his mother, Princess Diana, at such a young age and in such a public way, it all seems so tragic and terribly unfair," the author of "The King" said of the heir to the British throne.

Prince William and Kate Middleton
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge wave to well wishers as they leave after attending the launch of the King's Cup Regatta at Cutty Sark, Greenwich on May 7, 2019 in London, England.
(Photo : Ben Stansall - WPA Pool / Getty Images)

Another royal expert, Ian Pelham Turner, admitted to the outlet, "... I do not know how William can cope with fulfilling his duties and look after his family at the same time."

However, Andersen remained optimistic that Prince William and Middleton would be able to weather the storm.

"But if anyone personifies the royal stiff upper lip approach, it's Kate and William," the royal expert noted. "They have to remain strong and upbeat for their children."

Prince William and Princess Kate share three children: Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5.

Royal commentator Kinsey Schofield, who hosts the "To Di For Daily" podcast, also told USA Today that Prince William may feel like he's carrying the "weight of the world" on his shoulders at the moment as he takes on more royal responsibilities while supporting his family.

Prince William and Kate Middleton
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge arrive for their visit to Coventry Cathedral during their visit to the city on January 16, 2018 in Coventry, England.
(Photo : Christopher Furlong/Getty Images)

On Friday, Middleton announced via a video message that she was diagnosed with cancer after undergoing planned abdominal surgery in January. The type of cancer was not disclosed.

Middleton shared that Prince William has been "a great source of comfort and reassurance" amid her recovery from surgery and cancer treatment.

She explained that it took time for her and her husband to process the news and to explain it to their three kids.

Middleton also subtly addressed her absence from the spotlight, sharing that it took her time to recover from her major surgery to start undergoing treatment for cancer.

The Princess of Wales said she is currently in the "early stages" of preventative chemotherapy.

A spokesperson for Kensington Palace told Fox News Digital that Middleton will return to public duties "when she is cleared to do so by her medical team."

"She is in good spirits and is focused on making a full recovery," the spokesperson added.

Prince William, who took a brief break from royal duties in January to support Princess Kate and their family during her recovery, has continued to make appearances and take on engagements since early February.

Just last week, the Prince of Wales made an unannounced trip to Poland to meet British and Polish troops stationed near the Ukrainian-Polish border.

Prince William also attended a Homewards Sheffield Local Coalition meeting at the Millennium Gallery.