Then he should choose Chelsea if Chelsea officially comes for him, he has to let go of all those rivalry and loyalty bullshit. Already that have cause him to not have a successful ending career, assuming he went to Manchurian city as it was earlier started, we won't be here today discussing this because he would had been happy and playing good football just like his counterpart messi. Ronaldo's poor form at the world cup had contributions from his time at Manchester united and how it ended, he wasn't in form because he didn't get good playing times and the environment was toxic to him as he stated in those interview.
Meanwhile Messi was busy enjoying his time and not having much work of carrying the whole team on his shoulder since he had other superstar playing with him. Ronaldo needs a club he can relax and enjoy good football, Chelsea don't relay on strikers to score their goals so it might just be a perfect retiring ground for him and also we're still in the champions league which we're aiming to win.
As reportedly told and said by Fabrizio Romano, Cristiano Ronaldo trained with Real Madrid today as he currently prepares and trains fir the next level. If I'm to be frank here, Manchester United contributed to his poor form ahead of the FIFA World Cup leaving and keeping him on the bench to warm.
If he's to choose a side and I'm to be consulted, I would advise he get linked with a club and team that plays the Champions League football. Chelsea can offer him a short contract as they're currently short of a good Central attacker, Borja was recently out with surgery as I think he will surely be out for the season.
Chelsea football club are currently in the Champions League, why not make the switch to the London side after the breakfast and break up with Manchester United.