In 2018, Philippos began dating
Nina Nastassja Flohr, the daughter of Swiss businessman
Thomas Flohr, who founded the private jet rental company
VistaJet, and Katharina Flohr (
née Konečný), former Creative Director of
Fabergé and
editor-in-chief of the Russian
Vogue. That same year, they appeared together in public at the
wedding of
Princess Eugenie of York and
Jack Brooksbank. They made other appearances as a couple, including the wedding of Lord Edward
Spencer-Churchill and Kimberly Hammerstroem in 2018 and the wedding of
Jean-Christophe, Prince Napoléon and
Countess Olympia von und zu Arco-Zinneberg in 2019. In 2020 while vacationing in
Ithaca, Greece, Flohr and Prince Philippos became engaged. The engagement was announced by the former
Greek royal family's press office on 1 September 2020. They were married civilly on 12 December 2020 in a private ceremony in
St. Moritz, Switzerland. Due to the
COVID-19 pandemic in Switzerland, the only guests at the wedding were the couple's parents. A
Greek Orthodox ceremony took place on 23 October 2021, at
Metropolitan Cathedral of Athens. At this ceremony, Nina wore a wedding dress tailored by
Chanel and the diamond Corsage Tiara, which was worn by her sister-in-law,
Marie Chantal, at
her wedding. In attendance were Philippos and Nina's parents, siblings, nephews and nieces, as well as extended members of the Greek royal family, such as
Queen Sofía of Spain,
Prince Michael,
Princess Marina and
Princess Tatiana Radziwill. Other attendees included
Princess Benedikte of Denmark, the
Hereditary Prince and
Hereditary Princess of Hanover,
Prince and
Princess Christian of Hanover, the
Prince of Preslav,
Princess Beatrice of York,
Edoardo Mapelli Mozzi,
Princess Eugenie of York,
Jack Brooksbank and
Sabine Getty, along with her daughter, Gene, who acted as a flower girl. A reception was held at the National Gymnastics Association and another one at the Piraeus Yacht Club, hosted by Constantine. Οn 20 December 2024, Philippos along with the other members of the
former royal family acquired Greek citizenship, under the surname
De Grece. The family was deprived of citizenship in 1994 when the former King Constantine refused to acquire a surname, as required by law for all Greek citizens. == Titles, styles and honours ==