Bonas joined the 29-year-old prince at a public engagement for the first time on Friday, and on Sunday the pair were pictured watching England's victory over Wales at a Six Nations rugby match at Twickenham.
Public appearances by the royals are carefully choreographed and this weekend's activities suggest the relationship between Harry and Bonas, 25, is now official.
Harry, the youngest son of heir-to-the throne Prince Charles and the late Princess Diana, recently quit flying army helicopters for a desk job organising commemorative military events in London.
Speculation is mounting that he is ready to settle down -- just like his brother William, the second-in-line to the throne who married Kate Middleton in 2011 and had his first child, Prince George, last July.
The media first reported Harry's relationship with Bonas in July 2012, although the couple have taken pains not to be photographed together, arriving and leaving events at different times.
On Friday, the blonde dance graduate was not part of Harry's official entourage at a youth empowerment day but they sat together after he made a speech and were later photographed hugging.
A report in the Daily Mail's diary column on Monday said that Harry is planning to invite his girlfriend on holiday with the royals this summer.
His grandmother Queen Elizabeth II takes her annual holiday at her Balmoral estate in Scotland and an invitation to join the family there would be the ultimate stamp of approval.
Bonas, who was reportedly introduced to Harry by her friend and his cousin, Princess Eugenie, comes from a bohemian but appropriately blue-blooded family.
Her mother is Lady Mary-Gaye Curzon, a darling of the London social scene during the Sixties whose late father, Richard Curzon, was an earl who counted King Edward VII among his godparents, according to the Daily Telegraph.
Curzon was married four times and had Bonas with her third husband, entrepreneur Jeffrey Bonas, who is currently chairman of a haberdashery company, MacCulloch & Wallis.
Details are scarce about Bonas herself but she reportedly studied dance at the University of Leeds in northern England and now has a job in marketing in London.