I think it is very very difficult for a person who has not had experience with a spouse with MLC to understand the dynamics of a MLC relationship.
In a sense MLC is like a poker game that is rigged, no matter what happens you lose. That is to say it may be easy to find points of dissatisfaction that the person with MLC has with the spouse. One could make an argument that it is the LBS fault. Why did the LBS not change to meet the needs of the person with MLC?
However when you are in a relationship with someone who has MLC it really doesnt matter what you do, the person with MLC is unhappy. That is to say you offer them chicken, they say they dont like chicken. You offer them beef and they dont like beef. The food is either to hot or to cold. The person in MLC just plain doesnt like things. The MLCer has a long list of unmet demands, most of which have never even been verbalized. It is not unusual for the MLCer to blame the LBS for things over which they have no control. For example a MLCer might blame the LBS for the weather, for the fact the MLCer lost his job, or that their kids did not grow up to be corporate executives. No matter what has gone wrong it must be the LBS fault. More often than not the MLCer doesn´t like his job, doesn´t like his wife, and doesnt like his kids. So they build a fantasy where if they just meet the RIGHT PERSON they will find happiness. The first woman (or man) who throws themselves at them becomes part of the fantasy, and they run off together leaving the wife and kids to pick up and deal with the wreckage alone.
The thing about fantasies is that eventually they break down, and the MLCer is stuck with reality and has to start all over again. Only now they don´t have a job, or a home, or a family that loves them. They have thrown it all away.
However I think the key thing which defines the MLCer and differentiates it from a normal marital breakdown is the lack of empathy. In a normal marital breakdown it is possible to engage in reasoned conversation, and neither side necessarily wants to hurt the other. In MLC the MLCer is characterized by alternating coldness and rage and an inability to care for or about his family. The LBS is shocked by the lack of normal human compassion.
I am not saying that the LBS is perfect, I am just saying that from the beginning the LBS doesn´t have a chance. It doesn´t matter whether the LBS is perfect or not, they are still doomed to failure.