"I'm very happy," she said. "We're still friends and I talk to him on the phone all the time."
There was huge astonishment in showbiz circles after the top model decided to put their relationship "on ice" last March and she declined to comment any further about their romance.
Yet it's clear they have maintained their friendship and still care for each other, with Rosanna adding how she "doesn't talk about it."
Chris de Burgh's daughter opted to lie low for several weeks in the wake of the shock split, but has now returned to the social scene with a vengeance.
As well as hanging out with the stars in Monte Carlo, she was this week modelling for an international calendar for confectionery giants Lambertz.
And it certainly sounds like her saucy new pictures will leave her male fans drooling.
"The theme is chocolate mixed with eroticism. I just got back from Milan yesterday after the one-day shoot and I'm really looking forward to seeing the pictures. The shoot was in this furniture warehouse and the whole idea was to re-create this decadent scene with 18th century furniture so it should look really nice," she explained.
She added how she had an "amazing" time mingling with the big stars in Cannes and Monte Carlo, even nabbing an invite onto the multi-million euro yacht owned by Microsoft mogul Paul Allen.
Now she has her feet firmly back on home turf and will be looking forward to putting the nation's aspiring beauty queens through their paces next month.
She has been picked to co-host next month's Miss Universe Ireland pageant alongside Alan Hughes and Lisa Fitzpatrick.
"That's going to be an exciting experience and I know that, in retrospect, it's not as terrifying as it seems. It looks really good this year, the standard is very high. The winner will need to be confident and have an ability to express themselves -- it's just not about who's the prettiest," she said.
Asked about being involved in the rival competition to the Miss Ireland contest -- which first sent her on the road to stardom -- Rosanna said she was eager to help out an old friend.
"The time I won it, Andrea Roche had taken over the Miss Ireland franchise.
"I always saw her as a mentor and I wanted to be able to work with her for this competition," she said.
Socialite Andrea added how she chose the former Miss World as one of the hosts, as she is "someone that lots of girls look up to" and will benefit from her experience.
"Myself and Rosanna have worked together for seven years. We have a very good friendship as well as a working relationship. It's great to have her on board," she said.
Some 21 finalists will be lining out at Citywest hotel on June 26 when Lynn Kelly hands over her crown to her successor.
Although it's a scaled-down affair from last year, this year's bash will still be formalwear and covered by TV3, with oodles of goodies lined up for the winner.
However, beauty queen Lynn has warned that whoever does win the 2009 title will need to be tough, given the competitive nature of the industry.
"When I went to Vietnam to compete in the Miss Universe pageant, there were some nice people but there were also some people who weren't that nice," she told the Diary.
"A lot of those girls are competing in those kind of pageants from day one and take it very seriously whereas Irish girls would be far more relaxed."
Once Lynn hands over her coveted crown next month, she also revealed how she's heading to Las Vegas for a dream trip with her boyfriend Robert before heading to Cancun with a group of pals.