The Army Air Corps captain, who started dating Florence - or Flee - in June, wants to stay single because he has 'a lot on his mind'.
'He's concentrating on his Apache helicopter training,' says a source. 'After that, he's expecting to return to Afghanistan.'
Harry, 26, has been holidaying in Majorca, while Florence stayed in London, but the model is said to have tried - and failed - to convince him to go to Ibiza with her this month.
'Harry enjoyed spending time with friends over the summer,' the source tells the Daily Mirror, 'but he doesn't want to be tied down in a relationship when training, so he called time on Flee.'
Clarence House said yesterday: 'We do not comment on Prince Harry's personal life'