It took several weeks of bending her mind around the idea that what he loved was not her, but his version of her. 

Actually, most of us do this to one degree or another.  We find someone we think is "perfect" for us because of certain things that we think we see in them.  This is not generally a bad thing.  The problem is that sometimes our image of what we want is very far from the truth of the person we are projecting all this on. Most of us can sort that out as we go along and begin to see who the person really is and not just our projections.  Narcissists can't do that. They only see what fulfills their own wish of what the person they are with is like. 

My friend's guy was a very attractive, intelligent and savvy 40-something man whom had never been married, he said, because he kept meeting women who were "not available."  When he met my friend, he was very excited because she was very available, and quite lovely.  My friend is open, intelligent, and sensitive, and quite sensual.  He was easily able to draw her into his illusion of himself, because he seemed to be what she wanted.  He had many years of practicing the illusion that he himself had fallen prey to believing. By profession he was a women's "Coach" and offered workshops on achieving goals to women of the community.  He talked the talk of being someone emotionally aware, and spiritually attuned.

Here was my friends' biggest mistake; she opened her heart before she had enough information. She committed her love to him before she had spent enough time with him to gather the information as to whether he was really a good potential partner.  But, in her defense, she was taken in by a master at the craft of seducing women. He knew that he needed her to commit her heart quickly in order for him to be free to behave in accordance with his true nature. 

You see, once she had committed to him he knew it would be difficult for her to back out.  Human beings have a hard time changing our idea of what we think of someone once we have committed publicly to our view.  To have to say we were wrong about someone means admitting that we used poor judgment.  None of us wants to admit to that! 

So, even though my friend pretty quickly got a lot of information about him that indicated he was a poor partner choice, she could not easily say so without losing face. 

Fortunately for my friend, she had good advisors close at hand who could see through what was happening and help her regain her boundaries long enough to tell him she was through with him.  This wasn't easy, because people who are in love with themselves have a hard time admitting defeat.  His response was to insist that he would not give up on her and begged her to marry him.  Fortunately my friend had become strong enough at that point to resist his overt efforts at getting her to conform to his wishes; never mind what hers were.

How do you know if you're dating a narcissist?

I can tell you this, it's difficult to determine if a person is a narcissist very quickly because they initially are very intent on your perceiving them with the same allure that they perceive themselves. They will not want to show their true colors until they have a commitment. They tend to stay in pursuit mode, which means they want you to see them as wonderful as they see themselves and will go to great lengths to prove it.  That can be difficult for a romanticist to resist.