Women tend to be 'fixers', and can feel compelled to 'sort out' issues, whereas the average man is not particularly compelled to 'fix' a woman who constantly demands attentions and acts in childish, aggressive and immature ways.
Sadly, however, there are many 'good guys' out there who are more nurturing, who take on trying to please and look after their partners very seriously - and who consequently hang on much longer than they should.
Most narcissists aren't in therapy, and even if they are, may not be diagnosed as NPD.
Psychologists freely admit this, as well as the frustration and impossibility of working effectively with NPD's.
I believe any individual who is not comfortable within their own skin - therefore disconnected from their 'inner peace' - can develop narcissistic characteristics.
External factors such as race, class, income status or religion place no importance as to whether or not an individual will be narcissistic. There are three broad types of people living with inner pain and emotional insecurity (which applies to the greater community): No-one is perfect and this is totally understandable!
Most narcissists in therapy are forced there by the courts, or have arrived for 'other' reasons such as alcoholism or a divorce.
The effects of narcissism can initially be very subtle and deeply insidious.