You can’t always walk away from the narcissist.
I addressed this in Narcissists Are Made, Not Born
The usual advice in a relationship with a narcissist is to go no contact (if not to run away!) However, there may be several reasons to maintain a relationship with a narcissist:
You have children together, which means negotiating visitations, custody, and co-parenting issues.
You have a real parental or pseudo-parental responsibility to the narcissist (such as a step parent/child relationship, or a therapist/client relationship).
You have a pattern of creating relationships with narcissists, because of your own childhood experiences with a narcissistic parent. That is, to go “no contact” with one narcissist will only postpone your trauma until you recreate a new relationship with a new narcissist.
And for those who must co-parent with a narcissist, A.J. Kay has the following sage advice: