Very interesting....so what you are saying is that they have to go through the stages and then once they do they come out and are able to sustain their new self? Does the new self have to be a total opposite of the self that was unsustainable? For example when my H told me that for years he was doing what he was "supposed to do" means that he is done now of doing what people expect of him...uhhh...like be a father. So, eventually he could either be a father again or gain a new self that says...that is not what you really want?
Yes they must complete the stages to come to emotional health. The trick is they may never complete the stages, as their progression is largely unconscious and instinctual and they are not consciously aware of what they must do to complete their emotional development.
The new self is not a complete opposite of the self that was unsustainable. They're trying it on the extremes. Remember the pendulum goes to AND fro and if left alone eventually stops oscillating wildly but mildly swings in expected parameters.
He may become a father again or not. It all depends on how successfully he completes the stages of emotional development and if he has a lightbulb moment as to what he's really lost and is losing.