And how will their unwed status play to the crowd of official visitors or when traveling abroad, particularly to countries sensitive about male-female ties outside wedlock?
Will they simply break down and get married?
"This isn't something you do under the pretext that you're going to be president," Hollande said in an interview with the magazine Elle. "The decision is ours."
Trierweiler wants to keep working even though she has been booted from her job as a political reporter to avoid conflict of interest.
"Even if my press card is withdrawn, I will die a journalist. It's in my soul," she told Radio Hollande.
In her new role, she is walking through the other side of the looking glass, and she knows it.
"This role makes me a little uncomfortable, but I will manage very well if it is not limited just to that. I want to represent the image of France, do the necessary smiling, be well-dressed, but it shouldn't stop there. I will not be a trophy wife," she told The Times of London.
Carla Bruni-Sarkozy suffered legions of tasteless jokes about why she hooked up with Sarkozy — and more tasteless Tweets this week about whether she'll leave him now that he's out of power.
And she too struggled against the image of the trophy wife, according to Robb Young, author of "Power Dressing: First Ladies, Women Politicians and Fashion."
"On the world stage, of course, Carla outshone many of her first lady peers at the time, but this was more to do with the star power she accumulated during her years in the fashion industry and the natural charisma that no doubt helped to elevate her to supermodel status in the first place," he wrote in an email.
"What she spent most of her time as first lady trying to do — in terms of her style at least — was to downplay her inherent glamour quotient, detract from her beauty and whitewash some of her past by choosing rather demure and sometimes downright prim yet stately outfits," he said.
He noted that Bruni-Sarkozy had a career and world-famous name before ever marrying Sarkozy, and she has a foundation working to fight AIDS and other diseases.
"She will always be remembered for many more things than her comparatively brief career at the Elysee Palace," Young said.
Thomas Adamson and Cecile Brisson in Paris and Jocelyn Noveck in New York contributed to this report.
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