There is a difference between narcissistic tendencies and Narcissistic Personality Disorder, everyone has narcissistic traits, some more than others.
It's only when you spend a long amount of time with someone, like a family member or a partner that you can gauge whether it's more than tendencies.
In my experience, the behavior and abuse was consistent and went way further than someone who has narcissistic tendencies. It was full on delusional, changing personality on the fly for varying people, nice in public but hate filled at home and rewriting the past multiple times to become a victim, becoming a new person entirely over and over in order to avoid responsibility.
It didn't just extend to me either, it happened to previous partners, all of our friends and our entire family. Every bridge was burned through hatred.
Bear in mind also that people with NPD are not likely to seek diagnosis, they are perfect, everyone else is the problem, they have to be. So, by that basis alone, the statistics are likely skewed and even then they can mask and not be diagnosed. That's why generally I believe NPD usually get diagnosed when they have done so much damage or are in a position that they are forced to by third parties, they won't admit it themselves, they are perfect.
@Crossaintqueen Mine I believe is covert so wasn't all about possessions and flaunting it but they did in other ways. However, the ignoring your feelings rings true, doing things regardless of what you say and also the friends and family.
Mine has lost every single friend through their behavior, they eventually saw another side and it took over ten years for the mask to slip and that slipped when they eventually spent long periods together. Family, they found fault in every single person over the years and cut them off one by one until eventually they did the same to me and discarded me. Now they are alone but has my children isolated with them.
Listen to your gut, I didn't and she nearly destroyed me and is still trying.