The problems that the book tries to deal with are repetitious, where repeatedly, over and over, a couple bumps into the same issue, for example, the in-law problem just discussed. In the face of these repetitious problems, and only in the face of these repetitious problems, we recommend the kind of analysis in the book. You wouldn't want to go into this detail unless it's repetitious. This then often leads to some spontaneous positive changes. Another sign of an impasse is that things get worse, not better.
Every couple has difficult issues from time to time.
If there are children involved, that's an important consideration. The consequences in terms of financial standing is something couples consider. Obviously the couple married one year with no children and no property have an easier go at it than the couple who've been married for 30 years, have property and children and would suffer dramatic social and economic consequences were they to separate. The standard advice is to first try to solve their problems on their own. If they are unable to solve them that way, and they're getting worse, they should seek outside help.