A fascinating presidential campaign has ended in a classic confrontation between opposites: energy v elegance; right v left; man v woman.

However, the 44,500,000 French voters will also be confronted next Sunday with a choice between two odd couples. Not all of the French electorate is fully aware of the fact.

The troubled but once seemingly perfect power marriage between the centre-right candidate, Nicolas Sarkozy, 52, and his wife, Cecilia, collapsed in mid-campaign. Mrs Sarkozy, 49, is believed to have spent at least part of the past few weeks in Florida.

This has been widely reported in the foreign press and on the internet, but has barely been mentioned in the French mainstream press, and not at all on television. The only reference on radio has been in the daily foreign press review on France Inter which last Wednesday gave listeners translated extracts from an article on the Sarkozy marriage in the London Independent. The article asked why there had been an official news "blackout" on Cecilia Sarkozy's virtual disappearance from the campaign:

France Inter made no further comment.

France has strict, well-intentioned, laws which forbid the media to invade private lives. The president's wife, or premiere dame, is almost as much a part of the French political landscape as the First Lady in the US. Can the front-running presidential candidate's marriage therefore be regarded as a wholly private matter? Sources in Sarkozy's party, the Union pour un Mouvement Populaire (UMP) say there has indeed been another serious rift in his marriage . . . after brief appearances last Sunday, Cecilia has disappeared from view once again.

French internet sites are full of lurid speculation about the causes of the latest NicolasCecilia bust-up, the third in two years. The Paris political-media village is talking of little else, and some are asking whether the rest of the public do not have a right to know as well. Sarkozy's allegedly brutal and confrontational personality is one of the biggest issues in the campaign, but not the question of why his own wife would leave him at such a critical moment in his life.

By contrast, the unconventional private life of the other remaining presidential candidate, Segolene Royal, is well known to all. The 53-yearold Socialist candidate's 'marriage', and the exact nature of her relations with her partner, have been the subject of constant media speculation during the campaign.

Royal and her partner of 25 years, Francois Hollande, have four children; they have never married. He is also the first secretary of the Parti Socialiste. On the pattern of previous elections, he, not Royal, should have been the Socialist presidential candidate. The meteoric success of Royal in the primary campaign last year was a personal calamity for Hollande, 54. He behaved, in the circumstances, with extraordinary dignity.

He was, however, once caught on a live microphone saying: "I am living through a nightmare".

Hollande has let it be known he will not move into the Elysee Palace as First Gentleman if she wins. So are Segolene and Francois still truly a couple? They have barely been seen together in the last three months. Rumours have circulated for years suggesting that their 'marriage' is a sham, barely even a political alliance. Several times during the campaign, including in the past few days, Francois and Segolene have taken sharply different political positions. In January, Hollande said a Socialist president must raise taxes. Royal repudiated him. One of her closest advisers, Arnaud Montebourg, said soon afterwards on radio that the candidate's greatest liability was "her husband". Royal suspended Montebourg, but reinstated him.

In the entire campaign, they have been photographed as a couple only once. They shared a lunch, and a brief kiss, in the unromantic city of Limoges in late March. On another occasion, Royal was shown on TV embracing other Socialist leaders and then offering her hand rather coldly to Hollande.

In a book of interviews published last month, Royal joked about the speculation about her relationship, saying: "At least, since I am a woman, they can't say I have a hidden child somewhere." On the big question . . . are they still an item . . . she said: "Yes, we are together and yes, we still live together. If that was not the case, I assure you . . . given the paparazzi who follow us all the time . . . you would know about it."

Socialist party officials say she and Hollande have been targeted for months by the 'celebrity scandal' press in France, which systematically breaks the privacy laws and pays the modest damages. That raises the obvious question: why has this section of the French press ignored the Nicolas-Cecilia story?

One reason might be that Sarkozy has many connections in the French media industry. The last editor of Paris-Match was fired for running a picture spread showing Cecilia with the man with whom she fled to the US in 2005. The magazine happens to be run by a group owned by the media-business tycoon, Arnaud Lagardere, a close friend of Sarkozy.

When she left her husband for three months in 2005, Cecilia Sarkozy gave interviews to a journalist, Valerie Domain, who wrote a biographical book about it. Sarkozy intervened to have the book pulped before publication. Domain changed the names, added a few Mills and Boon flourishes and turned her book into a novel, Entre le coeur et la raison (Between heart and reason).

The book offers some clues to Mrs Sarkozy's recent behaviour. The Cecilia Sarkozy character, 'Celia', is presented as an impulsive romantic who cannot stand living with a man who ignores her, and leaves him. Her husband starts publicly dating a journalist (as Sarkozy did), and Celia is warned that she will lose everything . . . her child, her husband, the chance of being First Lady . . .

unless she returns. Celia reluctantly returns, but observes: "When you break a vase, even if you try to stick it together, the cracks will always remain."