The couple, who have previously done their best to avoid being photographed together, were seen gazing into each other's eyes at the WE Day festival on Friday and then watching England's win over Wales at a Six Nations rugby match in London yesterday.
Soon after bookmakers slashed the odds on an engagement announcement in 2014 to just 8/13.
The 29-year-old prince and 24-year-old dance graduate Bonas posed happily for photographers and kissed each other at Friday's charity event at Wembley Arena, where Harry joined Pakistani teenage activist Malala Yousafzai to address the crowd of over 12,000 students.
This was their first official outing together in the two years that they have been dating.
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Bonas, a graduate of Leeds University, is the daughter of 1960s model Lady Mary-Gaye Curzon and her ex-husband Jeffrey Bonas, chairman of the haberdashery firm MacCulloch Wallis.
She was introduced to the prince by his cousin Princess Eugenie and works in Soho in central London, where she has a job in marketing, and reportedly has a security pass for Kensington Palace, the prince's London home.