Another value of mine is not defining people by their worst moments. At first look, these might seem incongruous values but they're not - in fact, I would say that understanding this about me should help in overcoming any hesitation in working through mistakes. Taking ownership with someone who understands we all have our worst moments creates growth opportunities for all involved.
I suppose there are lots of reasons why people deflect and blame others for their own imperfections. A close friend who I've shared some of these challenges with has shared back with me something called oppositional defiant disorder. My friend was mostly talking about Donald what's-his-name, but I didn't have to look far to see some closer examples.