To be fair the situation with his daughter does explain the pre-season thing, and rationally or otherwise he's probably been seething about that since. Then he finds himself as a bit part player for Ten Hag and being criticised in the media nearly every week for holding the team back etc. Which for someone who's been seen as one of the best players in the world for 10+ years would be difficult to process.
Plus it doesn't help having idiots like Keane telling him he's right because they still haven't gotten over their own petty gripes with the club and are now projecting them onto Ronaldo.
Not that I'm defending him as such, but the interview is likely emotional rather than rational or calculated, and when you think of it that way it does seem a bit less bonkers. I feel a bit sorry for him as it does seem a bit like a publicly broadcast mental breakdown and it obviously isn't going to help him either.
But then also he sat in a room with Piers Morgan for 90 minutes and not only didn't punch him in the mouth, but didn't manage any better than a backhanded dig at Arsenal.