It is true that every sitch is different, but there are also many similarities.

Many MLCers pave the way to the affair by becoming involved in pornography at some level - not necessarily hard core, but unrealistic stuff that draws them away from a loving monogamous relationship, to put it mildly. I also see it as a profound spiritual crisis. I don't 'blame' the OP - after all it was our spouses' choice to hook up with them, but many of them are very very disturbed people that most people would avoid getting heavily involved with.

I am tempted to say that the craziness of the OP is an index of the severity of the MLC . . . if they are with a real loony tune they have a really bad case! But then a few MLCers do not have affairs at all . . . .