This is purely to do with will and love. People need to look for common ground - the thing that brought them together in the first place. Can they still be friends or find that warmth that they used to know?
The willingness of both parties has to be addressed. This is where councilling comes into play, where a mediator directs the couple toward gratitude and appreciation of the individuals that make a couple. The councillor peels back the sands of time, breaking down the emotional walls of discontent and clearing the disease of past misgivings. Once forgiving has occured, then there is room to move on.
Of course a relationship can break down with no return, but even so, councilling is important for both to close the chapter on a past life and love, especially when children are involved.
Yes, it is possible for any marriage to be saved, but is dependant on the willingness of the participants.