It is not that narcissists are incapable of expressing what we would tend to classify as “extreme emotional reactions”. They mourn and grieve, rage and smile, excessively “love” and “care”. But this is precisely what sets them apart: this rapid movement from one emotional extreme to another and the fact that they never occupy the emotional middle ground.
The narcissist is especially “emotional” when weaned off his drug of Narcissistic Supply. Breaking a habit is always difficult – especially one that defines (and generates) oneself. Getting rid of an addiction is doubly taxing. The narcissist misidentifies these crises with an emotional depth and his self-conviction is so immense, that he mostly succeeds to delude his environment, as well.