Yes, hostile and mean people are not happy! As to them not 'getting' why their children [and even their dog] no longer want to spend time with them. I think this changes slightly over time. Initially, like tad, and others, they are brash and entitled. The depression has apparently lifeted, and they are on a sort of high. They really expect the world to see things as they do, and are angry and I think even puzzled that they don't. The MLC high often seems like a drug high - they are truly in their own world, and own reality and morality.
Later, as reality sets in, and this takes a long time in most cases, they start sense a little that what they have done has been hurtful, but still justified to them. They sometimes try and makes amends, or build bridges, and convince themselves that all is well with their relationships with friends and family. It isn't of course, but the MLCer has something like a wall of glass bricks surrounding them, protecting them from any empathetic feelings. They are untouchable behind their wall of bricks. You can see them, and even shout messages through, but nothng touches them, much. And there they stay, cut off from all those they love and who love them.
Many of them drink heavily, prior to and during MLC, others get high on the OW, and the new and exciting lifestyle. You cannot engage with them, because they need to find thei rown answers. Damaged and damaging, as my xh once said in a rare moment of insight.
