"When I met Steve I was in this unhappy party-circuit bubble, which was quite unhealthy," said Millie of her rapper husband, whose real name is Stephen Manderson. "But he has brought out the best side in me: I feel happy and secure now."
"As an artist and a rapper he has a hard image," she added. "But I get to see a different side to him: he's kind, gentle, well-spoken – though I won't say he's soppy or overly sweet."
Stephen, 30, whose background in Hackney is a far cry from 24-year-old Millie's childhood in Chelsea, added that the couple's personalities complement each other.
"I was brought up by my grandmother, who said class isn't dictated by what you have in the bank but how you treat people," he said. "That's something Millie and I have in common: she's wholesome and she's got great values."
"I know I couldn't be with me: I'm an absolute nightmare," he added. "So I think Millie is commendable just for being with me, and she's helped me no end."
Stephen first met Millie after spotting her on the cover of FHM in 2011. The couple went on their first date at London's famous Groucho Club and hit it off straight away.
Two years later, after Stephen's "amazing" surprise proposal in Paris, the couple married in a romantic ceremony at Babington House in Bath.
Mille and Stephen were joined by around 120 guests including singer Lily Allen and Made in Chelsea stars Caggie Dunlop and Rosie Fortescue.
The couple, who live in London together with their pet dogs, both have busy schedules lined up in 2014.
Quality Street heiress Millie is set to show off her cooking skills on Celebrity Masterchef, while Stephen's new album, Growing Up in Public, will be released later this year.