Past hurt and pain can get triggered even when it doesn't have much to do with the present. When that happens we can gain perspective by self reflecting, engaging self empathy, grounding an "anchor", noticing the present-moment safety, naming needs and making requests.
What's really going on underneath the surface when we bring or encounter blame, judgements, pain -- and thereby the inability to empathize, be present, attuned, or responsive? Why does this happen even if one or more people in a relationship dynamic is working hard at bringing in an NVC response? This article addresses these and more questions from the perspective of how our brains are affected in our relationships.
One way to understand trauma is it means we got a blow greater than our nervous system can tolerate – then we move into hyperarousal, and then hypoarousal or dissociation. This cycle can continue long after. Here, we're not able to fully process emotional cues, information, our body, and others. It's important we consider re-writing the cultural paradigm of separation so that our trauma doesn't get marginalized.