Is a relationship with a level-four relationship stress level salvageable?
A relationship that's in level-four stress probably needs deep, deep therapy. What happens is, you forget how to communicate when you hit level four and it becomes impossible to go back to your corner and figure out why communication is broken down and to reawaken those great feelings you had in the first couple of stages of your relationship. That's the time when you need a third party to sit with both of you, take an evaluation of how you got here and calmly give it back to you so you can work on it alone together.