During the discarding phase they may dump you abruptly without any explanation or simply act as if you don’t exist whilst you are labouring under the impression that your hearts are still in sync.
The narcissist would usually discard you after finding new narcissistic supply from a secret affair or a fresh harem; at times it could be because your judgment of them has become clear and you can really see them for who they truly are. In this instance the narcissist would discard you as a form of punishment for being able to see beyond their false persona. They may also discard you because they found a new target with whom they feel entirely comfortable with.