I think he should stop for a year.
There seems to be a human factors problem here as opposed to just "ability".
Wife out the door, financial problems.....and the mental strain that goes with it, makes it sound like a case of fatigue.
I would suggest a complete restart in twelve months. If he has passed all the exams then there is no problem with is theory retention.
I know that there are some who will never get there but I think there's more to this than there seems.