I will jump in here on the difference between MLC and WAS.
First of all the LBS response to both is the same. No difference in what we do.
A WAS is a person who has been telling their spouse the issues and problems for a long time and has grown tired of telling them and eventually just walks away. Most LBS's turn into a WAS when they move to another relationship as they tire of their MLC/WAS and become the same thing, a WAS.
MLC is more of a development issue. Combine hormones, childhood issues, depression, stages of life, trigger event and you have an MLC. A perfct storm so to say.
Here is a thread from the resources to further read on the subject