Trusting, After many years at this, I have come to the conclusion that there are two main groups on the Boards [if you set aside the people who do not think that MLC exists at all] I totally agree with you and SA it is not an excuse, and that whatever their reasons, they need to be held accountable. But for some of us, understanding what is going on brings liberation, while for others it keeps them bogged down in their spouses drama.
I needed to understand WHY, and I now I largely do. That has enabled me to see it is not my problems but his. It enables me to feel some compassion [not invariably!!], and it enables me to move on. So while for you stopping trying to figure it out is the right thing, it isn't for all of us.
I have a very good friend on and off these boards, and she feels exactly as you do. We are both at about the same point, and we have recognised there are many roads out of dealing with MLC.
Continuing to love someone and let them go with sorrow and compassion is a hard thing to do, and many of us are on a rollercoaster with regard to this.