The role of first lady of France is not constitutionally defined. She has no specific legal status. Officially, she doesn't exist.
But when Valerie Trierweiler, a career woman who was not married to the president, arrived at the Elysee Palace, it posed double trouble for the palace protocol.
Who is she? The "first girlfriend", or the "first mistress" as some have called her? Ms Trierweiler, a divorcee with three children, and Mr Hollande, who has four children by his former partner, have never taken out a contract which would have formalised their relationship.
Ms Trierweiler, who was a political journalist with 'Paris Match' and a television presenter, initially intended to continue her professional activities as first lady. She has confided that during her first difficult year at the palace she sought advice from Michelle Obama. In the end, she agreed to confine herself to 'Paris Match's' book pages.
She has also taken on the more traditional first lady activities involving charity work. She is an ambassador for the human rights organisation France Libertes, set up by the late first lady Danielle Mitterrand, who is a role model for Ms Trierweiler.
As first lady, she is entitled to a private office at the Elysee, a bodyguard and access to presidential drivers.
She also recently opened an official Twitter account.
But ironically, it was just when Ms Trierweiler seemed to have adapted to her new role, that Mr Hollande's alleged love affair with an actress struck a blow, prompting fresh calls for the status of first lady to be enshrined in law. Mr Hollande yesterday ruled that out.
The role of first lady is certainly solitary. But some say that Ms Trierweiler has brought her troubles upon herself.
One co-worker said that as a journalist, she had lost support of colleagues by suing others who have raked over her colourful past.