I think that there is one very important thing to remember before grabbing for this "diagnosis".
Narcissists (Narcissistic Personality Disorder) are NORTORIOUSLY difficult to treat. As a matter of fact, you will be hard pressed to find one in treatment---unless literally forced by the judicial system or someone with a lot of leverage against them. Even in treatment--any changes or insight are usually rather minimal.
The reason for this being that, even though they can be insensitive and H*** on other people, they are exquisitely sensitive to the slightest criticism. They do not possess the ego strength for self examination that is often required in therapy. "Therapy" implies to them that they are flawed in some way--and therefore is very threatening.
Codependents are known to almost volunteer to accept quilt or take responsibility--where the true narcissist would rather die than do so.
We all have some of what could be called "Narcissistic" tendencies, sometimes, if we want to streeetch that label (LOL). It is a matter of degree. In the extreme, where it causes major disruptions or dysfunctions in the important relationships in our lives---it can then be called a disorder.
Of course, I am not the one saying this--the is paraphrasing from clinical writings by others on the subject.
Interesting note***I was married to such a person very early in my life---I got a divorce. He still hasn't changes one little bit!!!!!!
very sincerely, dandylion