This probably goes to the heart of why Cheung Mo Gei is described by many as "wishy washy," but I wonder why at the end of HSDS, he was so agonized about the decision to resign as Ming Cult Leader to be with Chiu Mun. Shouldn't this decision have been easy?
1. He already fully knew what Chiu Mun had sacrificed for him, and what he owed her, and knew he wouldn't be able to live with himself if he turned his back on her at that point after all that had happened.
2. He was never that crazy about being the leader of the Ming Cult anyway. He had originally agreed to become the leader only to save lives, and that job was done. Why was he reluctant to give up a title he had never really wanted in the first place and had never been comfortable holding?
3. His friendship with his Ming Cult brothers was an important consideration, but those guys loved and respected him anyway whether he was Cult Leader or not. That wasn't going to change if he vacated the leader position. They'd still hold him in high esteem.
4. Ambition to overthrow the Mongols and spread justice throughout wulin? Yeah, it'd be more convenient to do this from the position of Ming Cult Leader, but given Cheung Mo Gei's great martial art skills, the respect he commanded throughout wulin, and his likely position as third generation heir of Mo Dong Sect, he didn't absolutely need to be Ming Cult Leader to continue doing this.
So what was so hard about the decision that kept him tossing and turning in bed for days?