Ronaldo's relationship with Ten Hag deteriorated rapidly during the Dutchman's first few months with the Red Devils back in 2022.
After missing the club's pre-season tour while his desire to leave was widely reported, Ronaldo refused to come on as a substitute against Spurs and walked down the tunnel before full-time.
Ten Hag dropped him for the next game, and a month later Ronaldo sat down with Piers Morgan, where he said he felt "betrayed" by Ten Hag due to a lack of respect.
United announced Ronaldo's departure with immediate effect as the interview made the situation untenable, according to reports.
Ronaldo made 16 appearances for United under Ten Hag, scoring just three goals in what was an intense time at the club.
Speaking on his tenure alongside Ronaldo, Ten Hag suggested that the legendary forward did not apply himself in training, which may have led to his poor form and eventual departure.
"I confronted him with this," Ten Hag, who is now the technical director at FC Twente, said to The Athletic.
"Many times I say, 'Ronnie, everyone wants to work for you to bring you in the right position, but if you can't bring yourself in the box, you can't score.'
"He was not capable to do this. It's the wrong idea to put this to me that I expected him to do the pressing, that he's exhausted. But he couldn't. He ran neither in possession nor out of possession.
"The reason was because he didn't prepare himself."
Ronaldo has since stormed out of Portugal’s camp during the last international break amid a feud with manager Jorge Jesus, as he continues to create headlines at 41 years old.