OK Babylon, imagine if you said to me:
Wobbly, I was really upset what you said about me [and the bike].
Now, if I was NORMAL, I would feel what is was like to be that upset. I would remember the embarrassment of [me and a bike] and know how that felt, to look like a twat. So I would show the ability to EMPATHISE, to put myself in yours shoes. And, with that in mind I would feel sad that you felt bad and respond,
Sorry Babs, that WAS a bit of a thoughtless/harsh/whatever thing to say, I am sorry I made you feel [less that the wonderful person you are].
And we would make up. You would have felt heard, I would have thought about how you felt, problem solved water under the bridge.
Now, a narcissist has so much self-hatred, such an empty feeling within, that they cannot bear any criticism. They would feel such panic, shame and self-hatred that you saying how you felt, could not be borne by them. You saying that would be an ATTACK to get angry about.
So they would say 'no, I didn't. Anyway, YOU said that really horrible thing how could you be so mean... (denial, diversion, twisting, projection)
They will literally TRASH you and the relationship in order not to bear anything that is negative against themselves.
They will never, ever hear you, because they can't put themselves into your shoes and think about you.
Nrcissisism and affairs/midlife crisis/substance abuse go hand in hand, because those things don't require relationships. Bottles and pills don't have needs, mistresses tend to be on their best behaviour and very admiring and flattering.
It's the best way I can explain it.