Hi there SP - Its very very tempting to look for labels - in order to understand your W - I did too...I went through a stage of believing that my W also was in MLC - and that was a contributory factor in our situation...I realised though, pretty quickly, that regardless of the label, I had to deal with the here and now...the labelling of my W didn't benefit me at all save to give me a couple of days of self-delusional emotional relief - it didn't change the reality of the situation...
To robx - the cognitive dissonance works on both sides - for the person who is being left behind - CDiss can be created by 180s and acting AS IF - in that the LBS is not acting in ways in which WAW expects - this is uncomfortable and sets up WA with a challenge - she is wrong (crudely) and therefore has to do some re-working of her understanding of the relationship - rewriting history and also there are attempts to push the LBS into actions / behaviours which confirm her cognition - in which case that dissonance is dealt with.
If the LBS can stay strong in the face of this the WAW is left with a dissonance that must be resolved - generally the human mind cannot cope with dissonance - there has to be a resolution...a "reconfiguring" of one's cognition - that's why I suggested that its one of the most powerful tools.