The pair first started dating last July, but Cressida, 24, was left red-faced by Harry's naked billiards scandal in Las Vegas that August.
They kept in touch during his four months in Afghanistan, but only stepped up their romance since his return this year.
And, Prince or not, Cressida's not going to be embarrassed again.
'She treats him like a normal guy, not a Prince,' says our source.
'She's given him a deadline to prove he's serious because she doesn't want to put herself in
the limelight if he isn't.
'She's quite tough with him.
'She's asked him to delete his exes' numbers from his phone and to distance himself from friends she thinks are a bad influence.
'Harry likes that she isn't making it too easy and he'll do anything for her.'Â Â
The pair certainly seemed to be enjoying their ski trip.
Onlookers at the Pot Luck Club restaurant in Verbier saw Cressida perched on Harry's lap as they kissed 'like love-struck teenagers'.
Perhaps the impending arrival of William and Kate's baby has made Harry want to settle down, as the challenge of convincing Cressida to step into his very public life has clearly been on his mind.
Just last month he admitted it was difficult to find women who can handle the pressures of dating a Prince, revealing: 'I'm not so much searching for someone to fulfil the role, but looking for someone who'd be willing to take it on.'
It sounds like Cressida might up for the challenge...
Read more about Prince Harry and Cressida Bonas in Now magazine dated 4 March 2013 - out now! Â
 
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http://www.nowmagazine.co.uk/celebrity-news/542688/cressida-bonas-gives-prince-harry-3-months-to-prove-he-wants-her-and-only-her
