Why do narcissists start fights at random times and then refuse to talk to you until you "apologize" even though you did nothing wrong?
Narcissists seek control and power. Lack of emotion or the inability to process one's emotions might lead to irrational arguments.
Random fights can sometimes be used to gaslight you into thinking that you are the issue. Blaming yourself is a way to seize mental control while remaining in control.
Additionally, it serves to maintain you in the trauma-bonded partnership.
Nothing you say or do will alter the narcissist's coping strategy. The things you can control, such as your life and sanity, are up to you.