When does a covert narcissistic disordered person's mask slip?

...and not the Covid-19 mask - if it were that easy to distinguish them

It's in those quiet moments when you are with this type of person alone that their mask of the nice guy slips. Remember this – the covert narcissist has the ‘nice’ guy persona initially when you date him.

He says and does nice things to lure you into their fake fantasy of themselves as this great guy or girl but there is a hollowness behind their words. …