Calling the tune: Opera's Bonnie & Clyde

They are opera's golden couple whose romance flourished in the wake of tragedy. The tenor Roberto Alagna lost his first wife to cancer but found new love with the soprano Angela Gheorghiu.

It was a tale to warm the classical music heart and proved box-office magic. When they were paired for the Royal Opera House's production of Gounod's Faust two years ago, it sold out as soon as booking opened.

But ever since the Frenchman of Sicilian parentage and the Romanian diva first hit the headlines more than a decade ago, the backstage story has sometimes been less enchanting.

For even in a business where prima donna behaviour is an acknowledged hazard, their demands have added legions of new anecdotes to the records. They have even been nicknamed "the Ceausescus" after the late Romanian dictator and his wife, by their critics.

Both have fallen out with opera house managers amid claims of missed rehearsals and volatile behaviour. Gheorghiu, 39, was even said to have expected hair and make-up artists for an interview on Radio 3.

Yet even by the standards of opera, Alagna's decision to walk out of Franco Zeffirelli's production of Verdi's Aida at La Scala this week was extraordinary. In the highly charged atmosphere of the Milan opera house, he was by no means the first star to have been booed - even if most last longer than the first aria before the catcalls begin. Much-loved favourites including Luciano Pavarotti and Renée Fleming have suffered humiliation from the Milanese cognoscenti whose attitude to opera sometimes appears akin to a blood sport.

But Alagna's decision not to go on with the show made him the first singer in memory to leave the La Scala stage in mid-performance.

The opera house's management said yesterday he would not be returning. "His behaviour has created a rift between the artist and the audience, and there is no possibility of repairing this relationship," said a spokesman.

Alagna, in return, threatened to sue. "They are treating me like a monster, but I have not committed a crime," he said. "I've done nothing wrong. I went there to sing, to give the audience joy and pleasure. But what was I supposed to do when some people started booing?"

Surely, an innocent observer might speculate, that is the kind of supremely dramatic spat to be expected in the larger-than-life world of opera? It is not as if Alagna and Gheorghiu have been short of headlines in their careers hitherto. Quite the reverse. As early as 1995, when Alagna was first being touted as the fourth tenor (after the three tenors, Pavarotti, Plácido Domingo and José Carreras), he fell out with Jonathan Miller and the management of the Opéra Bastille in Paris.

The tenor missed rehearsals and unsportingly failed to applaud a fellow singer after she was forced to perform from a wheelchair after breaking her ankle on stage. Miller dubbed Alagna and his amour "opera's answer to Bonnie and Clyde".

Gheorghiu's disputes included a falling-out with Sir Georg Solti, her one-time mentor, when she refused to attempt some phrasing the great conductor had suggested for an aria from Verdi's Otello. And both have quarrelled with the managements at Vienna Staatsoper, the New York Met and Covent Garden as well as the agents who nurtured their early careers.

Joseph Volpe, then legendary general manager of the Metropolitan Opera in New York, cancelled a performance of La Traviata because he felt they had messed him around and publicly advised them: "Act like grown-ups and we will have a great relationship."

Even this year, Gheorghiu was said to have arrived late for rehearsals of Puccini's Tosca at Covent Garden with Bryn Terfel. It was the first new production at the Royal Opera House since Maria Callas wowed audiences 40 years earlier and expectations were high.

Some believed her temperament contributed to her failure to shine as Callas had shone. When Antonio Pappano, the musical director, subsequently spoke of his dislike of "capriciousness", his target was interpreted as Gheorghiu. It is certainly the case that she had been expected to appear in a forthcoming Don Carlos at Covent Garden conducted by Nicholas Hytner but has not been cast.

"Whether Alagna and Gheorghiu are the worst or not it's impossible to say," said one music insider. "There are lots of individual stories about the two of them, but there are some monstrous people in opera. It comes from insecurities. If you talk to anyone who knows anything about opera, Alagna shouldn't be singing the role of Radames in Aida. It's too big a role. You would have some sympathy and think he's been badly advised but he did take it on and in La Scala of all places. You've got to have the stomach for it."

Asked whether they were the most tempestuous couple in opera, John Allison of Opera magazine said: "The answer is yes."

There has been no shortage of operatic marriages - Thomas Stewart and Evelyn Lear, two of the finest Wagnerian singers of the 20th century; Philip Langridge and the Irish mezzo Ann Murray; Gerald Finley, the Canadian baritone, and the soprano Louise Winter; Dietrich Fischer-Dieskau, the bass-baritone, who proposed to Julia Varady by slipping her a note as he was strangling her in Puccini's Il Tabarro - but none has attracted quite the attention of Alagna and Gheorghiu.

Yet their turbulent high-profile may backfire. As Mr Allison observed, there are other singers waiting in the wings. Rolando Villazón, a handsome young Mexican tenor, has been creating sparks with his on-stage pairing with the beautiful Russian Anna Netrebko in operas including La Traviata at Salzburg and Rigoletto at the Met.

"Villazon and Netrebko are much lower maintenance and they're nicer for people to deal with," he said. "My guess is that the whole Alagna and Gheorghiu bubble has burst. Her voice is a more special voice than his, but there are lots of sopranos. He potentially has a scarcity value because good tenors are rarer than good sopranos. But if he starts walking out of productions, I don't think anybody will bother with him for too long."

Another source added: "I think they have just lost their grasp on reality. They think they're important and indispensable, but they're not really."

Curiously, though tempestuous as performers and interviewees, their own marriage seems comparatively settled.

Admittedly there has been speculation in recent years about the state of the partnership with their respective work often keeping them apart. They do not have children of their own, but care for his daughter by his late wife, and Gheorghiu's niece, orphaned by a car crash.

There have been fewer of the joint interviews of earlier in their passion when they could scarcely keep their hands off each other and when Gheorghiu confessed that making love calmed her before going on stage.

Yet both appear keen to sustain the fairytale that has been woven around them. "We are Romeo and Juliet every day of our lives," Alagna once said.

It is possible this rose-tinted view of life is a consequence of their far from rosy beginnings. Both come from backgrounds far from the glamour and wealth of opera. Alagna is the son of a Sicilian bricklayer who was turned on to opera by seeing Mario Lanza in The Great Caruso. He tried singing at a pizzeria cabaret where his untutored talent was, miraculously, spotted by a singing teacher. He went on to win the Pavarotti Competition in Philadelphia and embarked on a glittering career which first brought him into contact with Gheorghiu in La Bohème in 1992.

Both were married at the time. But after his wife died from a brain tumour in 1994, Gheorghiu left her plumbing engineer husband in Bucharest and the couple married two years later.

Unlike Alagna, she had always dreamt of being an opera star. Though the daughter of a train driver, she studied music from an early age and was a star in her native Romania by the age of 18. The ending of the Ceausescu regime ended just in time for her to embark on an international career without travel restrictions in 1990.

Solti, who launched her on London in La Traviata at Covent Garden four years later, hailed her talent: "The girl is wonderful. She can do anything!" The audience reaction to that performance was such that the BBC cleared a whole evening of BBC2 to transmit the next one live.

Critics called her "a diva to die for" and some still do - though possibly with caveats today, with reports of prima donna tendencies casting something of a shadow on her work. Yet until this week, Alagna had grown to seem a less tricky customer. Not after walking out of La Scala after just 10 minutes. "It's a disastrous career move," Mr Allison said.

In these days of ever-tighter budgets, opera houses seem less forgiving than they once were of bad behaviour. They want their stars punctual and amenable - and they even want them to look the part. In an image-conscious society, the fat lady no longer necessarily gets to sing the consumptive heroine.

The tide began to turn as long ago as 1994 when Joseph Volpe fired the soprano Kathleen Battle from the Met after a much-publicised run-in. And when the conductor Riccardo Muti pulled out of a production of Verdi's La Forza del Destino at the Royal Opera House at the last minute two years ago, its management gave very public vent to its fury.

The La Scala management said yesterday that it was considering Alagna's position but added: "A professional can only leave at the end of the performance or in case of serious accident. He left intentionally and therefore he broke his contract with the theatre and the audience." The tenor himself insisted the public still wanted him and that La Scala had been in the wrong not to protect him.

"They are the ones lacking respect towards the public if they don't let me go back," he said. "I have another five performances to do, and the audience is waiting for me." The issue may be whether they want him enough. In the eyes of some in the opera world, its stars have got smaller. Gheorghiu is no Joan Sutherland, Montserrat Caballe or Callas. Alagna has not turned into the next Pavarotti.

"Neither Alagna nor Gheorghiu are in the same league as the stars [of the past]," Mr Allison said. "And the world has changed. People just don't get away with this kind of behaviour any more."