The former Tottenham Hotspur player pleaded with Manchester United to persuade their star player to remain, but he also admitted that he understood Ronaldo's desire to leave Old Trafford before the 2022–23 season.
"Cristiano Ronaldo was their top scorer last season," O'Hara told talkSPORT.
"He stepped up in big moments for the club. He's left because they think it's a sinking ship.
"They're a shambles for letting him leave. He carried that team for months. He's earned the right to say, 'This isn't right, the future is not bright with Manchester United, I want to win trophies'."
TV commentators and former players Gary Neville and Jamie Carragher were the first to talk about the issue on Twitter.
Ronaldo, according to Carragher, "scored goals, but made the team poorer," which is exactly what he expected he would do. This generated a response from the Red Devils legend and an instant reaction on social media
Several European clubs indicated interest in hiring the Portugal captain after his intentions were made known.
The three teams with the best chances of landing him are reportedly Chelsea, Barcelona, and Bayern Munich. The new owner of the Blues, Todd Boehly, has already spoken with Ronaldo's agent, Jorge Mendes, about a potential contract for the upcoming several seasons.