The pair first started dating last July, but Cress was left a little embarrassed by Harry's naked Vegas scandal back in August. They kept in touch during his stint in Afghanistan and their romance blossomed upon his return - but it seems that Cressida is one tough cookie and is determined not to be left red-faced again.
A source allegedly told Now magazine, "She treats him like a normal guy, not a Prince.
"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."
To help Cressida out (we're nice like that) we've put together the ultimate 'Make Sure That Prince Is Serious' action plan to get her started:
Tell Haz to quit getting his tackle out in drunken games of naked billards (posh people's strip poker) in Las Vegas.
Get the Prince to buy you some kind of commitment jewellery that clearly identifies who you are when he gets a bit squiffy. We're thinking a necklace rather than a ring, that way he'll know which blonde you are (i.e. NOT Chelsy Davy) at all times.
Make Hazza get rid (read: burn) his questionable dressing-up box. That Nazi thing really can't happen again. If he loves you he'll understand.
Rinse and repeat. Okay that's not applicable here, but step four should be to make sure steps one, two and three are carried out accordingly.
Take a look through the below gallery to remind yourself you are currently dating THE most eligible bachelor in the land (bar Harry Styles)...