The 29-year-old has grown frustrated by the transfer policy at Madrid and now has his heart set on a return to Manchester United in 2016, meaning he will be unlikely to come good on a previous promise of finishing his career at Real. When he put pen to paper on a new contract only last September, it seemed as if he was signing up for life. But things change quickly in football and, following a summer which saw both Angel Di Maria and Xabi Alonso leave the club against his wishes, Ronaldo has also questioned his own future.
The former Sporting player arrived as the cornerstone of an ambitious new project under Florentino Perez in 2009. "The excitement has returned," the campaign slogan read. And when the construction magnate was confirmed for his second spell as president, he made some bold claims. "We want to recover our place in history," he said. "We want to make this club a point of reference across the world. We are going to build a Real Madrid side made up of the best footballers in the world. Every game will be a fascinating affair. We want not only to win, but to win convincingly."
It sounded good. Karim Benzema, Xabi Alonso and Kaka also arrived that summer in a total outlay of more than €250m. But Barcelona claimed their second successive Liga title under Pep Guardiola and Madrid, despite racking up what was then their highest-ever points total of 96, finished second. On top of that, Manuel Pellegrini's side suffered a humiliating 4-0 defeat (4-1 on aggregate) to Segunda Division B team Alcorcon and were knocked out in the last 16 of the Champions League by Lyon. Some of the excitement may have returned, but the club ended up without a trophy and the Chilean lost his job.
Jose Mourinho succeeded Pellegrini and under his compatriot, Ronaldo became even more prolific, netting 53, 60 and 55 goals in their three seasons together at the Bernabeu. But those three campaigns brought just three titles: the Copa del Rey in 2010-11, La Liga in 2011-12 and the Spanish Supercopa later in 2012. Cristiano was fundamental in all of them, heading the winner at Mestalla as Real beat Barca to the cup, netting 46 goals en route to the Primera Division crown and converting in each leg of the Supercopa success.
But Mourinho had been brought in to win the Champions League and the Blancos fell short of that goal on three successive occasions, losing semi-finals to Barcelona, Bayern Munich and Borussia Dortmund. And folloiwng their 2-0 loss to the Catalans at the Bernabeu in 2010-11 in which Madrid had less than 30 per cent of the possession, Ronaldo publicly criticised his coach, telling television reporters: "This is not how I like to play football."
Most of the fans agreed and it was still far from the side Perez promised would become a "point of reference throughout the world". That team, much to his frustration, was Barca.
The appointment of Ancelotti brought stability and tranquillity following the turbulent times of the Mourinho era, but more meddling from Florentino saw Mesut Ozil sold against Ronaldo's wishes. Nevertheless, a season that began badly ended in spectacular style as Madrid won the Copa del Rey and - at long last - La Decima.
The Uefa Super Cup has since been added, but Real are still struggling to find the midfield balance without Alonso and Di Maria, are down in 12th place in La Liga after back-to-back defeats and also lost out to Atletico in the Supercopa. "I will find the solution," Ancelotti said recently. But he had already found it - and now he has to start all over again. Cristiano is not amused.
Ronaldo won the Premier League in his last three seasons at Manchester United, but he has still won only one Liga title in Spain and six trophies is a slim return at a club that was supposed to rule the world following the return of Perez. With 257 goals in 252 games, he has done his bit to secure success for Real Madrid, but believes the club could have done much more to make the final step up and dominate domestically and in Europe. So if he does leave Real over the next year or two, many may wonder just what might have been if Madrid's ambitions had matched those of their finest footballer.