I think that Meyer honestly believes he did nothing wrong in the Zach Smith domestic violence mess. He feels that Ohio State should have backed his position, and feels that Ohio State instead disrespected him with the 3 game suspension. I think Meyer knew then that he was leaving. He stuck around because he hoped to win a National Championship and thumb his nose at Ohio State when he resigned.
I think that Meyer intentionally leaked that he was "retiring" approximately 2 weeks prior to the early signing day in hopes of hurting Ohio State's recruiting class. If he loved Ohio State, he would have delayed making it known until after the early signing period.