Why do relationships sometimes end in bitterness, with people turning vicious?
If you look at it through the lens of the nervous system, the answer becomes clearer. Breakups are not just emotional, they’re biological. When two people separate, especially after deep intimacy, the nervous system can interpret it as a threat. There’s a lot at stake, emotionally, psychologically, and sometimes materially. That high-stakes environment easily triggers the fight-or-flight response.
When individuals aren't self-aware, emotionally regulated, or actively working on their healing, reactivity skyrockets.
There’s also a huge amount of fear at the end of a relationship, fear of being alone, of abandonment, of loss of identity or security. And as a survival mechanism, resentments flood to the surface. Why? Because to break the emotional bond, the brain often pulls up everything that ever hurt, every slight, every disappointment, every unmet need, as fuel to disconnect.
That’s how we sever intimacy: we focus on what made us angry.
Then things often get ugly. People fight over money, possessions, power, all symbolic extensions of control and self-worth. If the relationship ended due to betrayal, like cheating, the injured partner may experience a strong drive for revenge. And while overt revenge is rare, subtle revenge is common: badmouthing, stonewalling, passive-aggressive behavior, withholding, or emotional outbursts.
If we stay on the concept, that anxiety plays a massive role and these vicious endings what we should learn is that the build up to the end of a relationship could unravel the nervous system and bring people to the absolute extreme reactivity.