I think DBing is always a success even if it isn't enough to hold a marriage together. You never lose anything by trying, and the lessons themselves (GALing, 180s, positive attitude, etc...) are very healing. Even if a marriage ends you would at least know you did everything possible to try and keep it together. (Can't regret that!!!) And that is a type of success.
There is no arriving, ever. It is all a continual becoming.