The French leader is currently at an EU summit in Lisbon, the Portuguese capital.
The couple have rarely been seen together since Sarkozy took office in May.
Cecilia played no public part in her husband's election campaign this year and did not vote for him in the second round of polling.
She only appeared alongside him at three public engagements since his May election victory - the last time in July.
Asked about her possible role as the president's wife, she said two years ago: "I don't see myself as a first lady. It bores me. I'm not politically correct."
Her last public appearance was in September at the funeral of Jacques Martin, her first husband.
Due to legal constraints, the French media have not been able to discuss the couple's problems.
But on Thursday, the change in coverage was dramatic.
Liberation, a daily newspaper, published a headline reading "Desperate Housewife", beneath a full-page picture of Cecilia.
All the weekly magazines also carried the couple's problems on their front pages.
Cecilia played a crucial role in Sarkozy's rise to power, serving as an adviser during his previous roles as interior and finance minister.
Sarkozy himself boasted of the strength of their relationship, telling aides she was "the only non-negotiable part" of his career.
Their relationship problems began in 2005, when they both had affairs and briefly lived apart.
He was visibly shaken by the episode, losing weight and appearing irritated, and questions were asked about his ability to govern under emotional duress.
However, the couple got back together again at the start of 2006 and Sarkozy wrote soon afterwards that he expected they would stay together.