Time and silence are two time tested weapons which never fail.
Silence : Not only your girl/boy friend, to calm down any one, give them time to introspect and you remain silent in the said period.I call this three day cool off period.
We are rational human beings with irrational bouts of emotions. We often destroy the relationship by giving them additional inputs while some body is angry.This is just like adding fuel to fire.This leads to misunderstandings, fights and trauma.
Angry person is never rational. Ask any one who had breakup during a fight.They always regret.
Speech is silver but silence is golden.
Point 2 : Time is greatest healer. It heals every thing even broken heart except broken trust. We have positivity bias inbuilt with in ourselves. We tend to forget the negative details over time.