As we know, narcissists have no empathy for other people, common decency or shame about how they treat others, and it seems that the closer they are, the worse they behave. This is more prevalent within an intimate relationship where they have an intrinsic prerequisite to manipulate to the point of total control and coerciveness.
Their conceited haughtiness is unbelievably self-centred. They can play with a partner like a cat does a mouse, they can play unkind emotional games in order to methodically destroy their target, who is more often than not, an empath. They are actually destroying the disowned part/s of them that they cannot recognise as themselves.