Miss Bonas, 25, who friends described as "laid back", had always found it difficult to cope with the attention of being a princess-in-waiting.
One well-placed source said the couple have "paused for a breather", suggesting that they could eventually get back together as did the Duke and Duchess of Cambridge, who also separated for a period before they eventually married.
The Prince, 29, spent yesterday at a recovery centre for wounded servicemen, promoting the Invictus Games, the Paralympics-style event that will be held in London in September.
Photo / AP
He showed no signs of strain as he laughed and joked with soldiers who hope to compete in the games.
A source told The Daily Telegraph: "The relationship has certainly at least paused for a breather. It is virtually impossible to have a successful romance and relationship in the full glare of the world's media."
Asked what might happen in the future, the source said: "It's impossible to say because I don't think the two of them know either."
Speculation that the couple might marry reached fever pitch last month when Miss Bonas accompanied the Prince to an official engagement for the first time.
The couple kissed and hugged at the event in Wembley Arena attended by 12,000 people, which was interpreted as a sign that they had grown more confident in the strength of their relationship. Two days later the two were again out together in public when they attended a Six Nations rugby match at Twickenham.
However, they have not been seen in public together since, and one report last night suggested it was Prince Harry who had ended the relationship because he found Miss Bonas "too needy".
The Daily Telegraph reported at the time of the couple's public appearance that Miss Bonas had told friends she was not ready to settle down. Miss Bonas, who works in marketing but studied dance at university, harbours ambitions of a career on the stage. She was said to be "wrestling" with the knowledge that she would have to choose between acting and the Royal family. A friend said at the time that: "People talk to her about Harry and she gets quite cross and says 'I don't want to get married yet'."
Sources close to Prince Harry said recently that "if it was up to him he would get married straight away", suggesting it may have been Miss Bonas who called for a time-out.
The Prince had told Miss Bonas he would wait until she was ready to make a decision, and lately she had decided to "get a grip" and accept the inevitable attention that her relationship brought.
The fact that the couple had not been seen together since their highly public appearances at the beginning of March suggests that the worldwide media coverage of the events was instrumental in their decision to call it a day.
Although their appearance together at the We Day event in Wembley seemed to have been part of a pre-planned strategy to go public with the relationship, sources close to the couple insisted at the time that "it just happened" and was not an attempt "to make a statement".
The public appearance had been in marked contrast to Miss Bonas' previous attempts to avoid being photographed with Prince Harry, though friends have said that her reluctance to pose for pictures is down to shyness.
The couple were first introduced by Princess Eugenie, a close friend of Miss Bonas, in the summer of 2012.
As well as putting her acting aspirations on hold, Miss Bonas has turned down well-paid modelling jobs because she fears that "it's only her royal connection they're interested in".
