The way I understand it, there's vulnerable narcissism and grandiose narcissism. Neither of them are prone to seek help, but the grandiose type may admit it and be proud of that fact, while not seeing it as a problem.
Although they both certainly crosses gender lines, the vulnerable narcissism is more typically associated with females and the grandiose with males.
I checked the article, and it's pretty weak sauce. In my opinion, a healthy narcissist will feel great about his/her accomplishments, but will not try to feel entitled to different treatment. An unhealthy narcissist will play up his/her accomplishments from a base of insecurity about the accomplishments. Similar to the difference between a loud talker and a quiet doer (tortoise and the hare - sort of thing).
So you actually have to ask two questions:
1) If they are special or superlative or whatever. That's the question everyone asks. Evidently, since being good at everything is impossible, asking what they're bad at or what they need work with is usually a good tell.
But the second one is even more important
2) If they feel entitled to special treatment (you'll also see that in their behavior).
Everyone is superlative at something. Some are superlative in things that provide revenue. Among the high achieving, it happens a lot that praise given for doing particular things right over a lifetime manifests into a bit of an inflated ego.
But the main thing you have to see is in the little things. How do they treat the valet? How do they treat the help? How do they behave when things go wrong? Do they politely wait or do they berate the attendant? Do they assume that people who are in a menial job are there because of their "low capabilities" (whatever that means) or do they afford them respect?
A vulnerable narcissist is a bit of a different beast. Their base is shame, and the insecurity comes from the shame. And because of that, they shy from self-describing as feeling important. But the behaviors are similar - they are very nice to people they want to use, and lose touch with people that aren't useful to them. They hide their As even from their friends and family. They act caring but are internally perfectionists, and when you are not as perfect as they expect you to be, they then act out when they are disappointed instead of addressing the issue head on. They also expect special treatment but never tell you, instead they feel offended and swing back and forth between inferiority and superiority depending on what's going on in their life.
But both types will avoid contact with therapists, or feel angry/put upon/defensive when speaking to one. Vulnerables may seek help but only during the crisis.
You walk on eggshells with both for similar reasons. With the grandiose, you're more afraid of the anger outbursts. With the vulnerable, you are more afraid of their oversensitivity and offending them.
They are both incapable of empathy, and unable to provide real emotional support, unless they take a serious look at changing and go through long therapy.
Narcissism and Bipolar go side by side with affairs.
But as you resolve this in your head (same thing happened to me - asking "what the heck happened??", one thing is important - don't tell them, don't try to diagnose them (we're not qualified), don't concentrate on it so much. It just enables them, as it continues to be about them. Focus on yourself and your healing. If he's a jerk he's a jerk. We can feel sorry for them as fellow human beings, as we do have empathy. But let him suffer his consequences. Let him figure himself out.
Healing from being long term with a NPD/BPD is hard enough as it is concentrating on ourselves. Don't give him any more mental bandwidth than is necessary to heal your own self. Don't talk about this with him, it will just backfire.