While his doctorate is not in mental health, this well-informed author clearly did his homework and writes from experience. Dr. Vaknin's CV is published here. His book, and much more, is available in hard copy or download on his main web site . It is precariously balanced. Being abandoned could cause a narcissistic injury so grave that the whole edifice can come crumbling down.
Narcissists usually entertain suicidal ideation in such cases.
BUT, if the narcissist initiated his abandonment, if HE directed the scenes, if the abandonment is perceived by him to be a goal HE set to himself to achieve - he can and does avoid all these untoward consequences. The narcissist denies his reality constantly. The narcissist's partner is perceived by him to be a source of narcissistic supply, an instrument, an extension of himself. He considers his very existence as sufficiently nourishing and sustaining to his partner. He projects sickness unto her.