Austrian Princess Maria Galitzine has suddenly died of an aneurysm - an excessive localized swelling of the wall of an artery - leaving behind her two-year-old son and husband.
The descendant of the country's last Emperor Karl, who died 98 years ago, lost her life at the age of 31.
She died on May 4, just six days short of her 32nd birthday, of a cardiac aneurysm.
Princess Galitzine had been living with her partner chef Rishi Singh in Houston, Texas, and her son Maxim.
Her funeral was on Friday and her death was confirmed in an obituary in the Houston Chronicle on Wednesday.
It read: "Our Maria passed away in the Houston morning of Monday, May 4th, 2020, from a sudden cardiac aneurysm."
Princess Galitzine was born in Luxembourg City to Prince Piotr Galitzine, a Russian aristocrat, and Archduchess Maria Anna of Austria, the daughter of the Archduke Rudolf of Austria.
Her grandfather was the youngest son of Emperor Charles I of Austria and Empress Zita of Bourbon-Parma, who had been exiled from Austria following the end of WWI.
She was one of six children.
Princess Galitzine's great-grandmother Zita went on to live until she was 96 and was granted special permission to be buried in Austria.
It was not a state funeral and the public reaction to the decision was mixed, Tatler reported.
The princess's sister Tatiana said that they had been brought up normally.
The only time their regal status was noted was when they were invited to royal weddings, The Houston Chronicle reported.
Princess Galitzine lived with her family in Russia and attended the German School of Moscow, before moving to Belgium to study interior design at the College of Art and Design.
She moved to Brussels, Chicago and then Houston, where she met her husband.
Their son Maxim, who is described as the 'apple of her eye' in the obituary, was born shortly before the couple's wedding on February 10, 2018.
Despite her royal background, Maria looked to live a "normal" life and this was a philosophy shared by sister Tatiana.
Speaking about the "weirdness" of this life, Tatiana said: "My life is completely normal unless we are invited to royal weddings.
"My mail sometimes says 'Princess Tatiana.' What was weird was when I went from 'Princess' to 'Mrs.' I had been a princess all my life."