On a larger scale, this is how we get into wars. We become afraid. We fight or run away. Fighting or running put us in conflict. Inner conflict causes outer conflict.
Outer conflict causes war.
Perhaps if you take a closer look at those times you've been in conflict, you can better understand what was going on inside you. Think of the last time you witnessed a fight or took part in one. This could be a physical or verbal fight. Sometimes we decide to stay and face the action that causes us conflict, and sometimes we decide to run away from it. We all make such a decision based on our drive to survive.