anyone can be violent.. but generally they try to assert their power and control over others - or just try to show how important they are... and get approval from others... dunno about violence... and yes you're right. it stems from the childhood because they didnt' receive the attention and nurturance that a child needs growing up... a child needs praise to build their self-esteem but narcs don't receive that so they try to give it to themselves...

I have also heard that a poor attachment may be complicating the issue. And that this personality disorder is one of the hardest to treat. Are narsisstics sometimes violent?

I would suggest marriage counseling in addition to individual therapy. the Narcissistic person needs intensive individual psychotherapy to deal with the childhood traumas (such as neglect or maladaptive coping mechanisms) and attend marriage counseling with his/her spouse to address the marital conflicts due to his/her narcissistic behavior.

I wouldn't give up hope if the spouse loves his/her significant other and is willing to work together to resolve past issues and save the marriage. it's hard work, but I think it's doable.

What about the effects on the spouse? What does living with a narcissistic person mean? Do most people stay in the situation or do they get out? If they do either, how?