You walk away from a conflict between you and another person when things are not getting resolved.
You walk away or run if another person is going to abuse you verbally or physically.
You walk away when the conflict is between other people, they are safe, and it is none of your business AND you have no way to help them or your help is unwanted.
You walk away when the conflict is really trivial.
You never walk away when children are involved and the child needs protection or removal.
You never walk away when a women is being abused or about to be abused. You take her with you and tell the man or other person to cool down.
You walk away when you yourself feel like getting violent or verbally abusive.