Trierweiler, France's de facto First Lady, has been in hospital since Friday with stress linked to last week's revelation that he has been having a liason with Julie Gayet, a blonde actress 18 years his junior.
Hollande said that the issue of whether Trierweiler accompanies him on an official trip to Washington next month would be resolved before then. The couple are due to spend a night at the White House as guests of Barack and Michelle Obama.
Asked directly if Trierweiler was still France's First Lady, he replied: "I understand your question and I'm sure you will understand my response.
"Everyone in their personal lives can go through tough times. That is the case (for me). These are painful moments.
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Media reports claimed the former journalist was suffering from low blood pressure, exhaustion and a "severe case of the blues."
She had initially been expected to be discharged after three nights but aides announced yesterday that she had been advised to extend her stay, saying "doctors believe she needs more rest."
Friends and political allies of Hollande had urged him to move quickly to clarify the situation by stating clearly whether he is still in a relationship with the woman who has been his girlfriend since 2007.