I think this is the most likely reason for the whole situation here. This aligns with both side of the story and the whole timeline too.
April/May - it’s already clear at that point we won’t have CL football next season. Should Ronaldo decide to leave for CL, he should have already requested for a move at this point
July - Ronaldo has reported requested for a move for CL football and then went missing the whole preseasons (for family reason). But why leave it this late? Could it be because ETH has already talked to Ronaldo and couldn’t guarantee him as starter?
July/Aug - Club has repeatedly announced Ronaldo is not for sell, despite lack of serious interest from any takers. ETH emphasised Ronaldo is key part of his plan.
Nov - Ronaldo finally went out public against the club/manager. His main complaint being the manager not respecting him and bullshiting him while not letting him playing a bigger starting role this season. He also said he didn’t really want to leave Man Utd in summer, despite “several” clubs shown interest for him.