Narcissism is a personality disorder that is characterized by an exaggerated sense of self-importance, a lack of empathy, and a constant need for admiration. Narcissists often believe that they are superior to others and deserving of special treatment. They may also have a sense of entitlement and expect others to cater to their needs and desires.
In a relationship, a narcissistic partner can be emotionally manipulative, controlling, and prone to anger if they don't get their way. They may be critical and dismissive of their partner's feelings and needs.