I'm beginning to think there's a "trigger" for those minority/few cases that cannot be explained, or lack warning signs.
IMO, based on what has been published from accounts by CB and PF's former girlfriends, there were warning signs. The problem was that apparently people close to PF did not recognize them, or chose to ignore them, and some even enabled him in continuing the abusive behavior. Maybe we'll find out if PF's abusive behavior ever rose to the level that warranted action by LE, but wasn't reported or not followed through.
However, it seems a good many psychopaths can keep their abuse just below the level that breaks the law--for a long time or even forever. That's why it is so important for the friends and family members of victims to at least try to intervene. I understand that psychopaths are masters of deceit, manipulation and brainwashing, which results in victims not really understanding they are victims. Our society needs so much more education on this topic so that we all--victims, friends and family--have a better chance of recognizing what's going on in order to help ourselves and each other. Like with "Me Too," I think this awareness will be led by women.
So many of us mothers and grandmothers who have "learned the hard way," can start with our own daughters, sons, granddaughters and grandsons. I once stepped in and lambasted my teen son right in front of his GF because he swore at her. I told him never to speak to any girl / woman like that again. I told his GF never to allow any
boy / man to speak to her like that. I was angry and did not hold back or sugar coat at all. Too often, people just want to mind their own business and look away because of embarrassment. Everybody, call them out, every single time, and of course, the same with child abusers. I agree with the posters who commented that partner murder is getting worse. Abuse, in whatever form, starts at a low level and escalates, often unchecked, until it finally results in murder. I don't think it suddenly erupts out of nowhere. Abuse at every level and in every form needs to be checked. MOO.