Authentic relationships form when two people connect via their core. In intimacy, each person sees the other person for who they truly are, flaws and all. Each person feels the other and empathises with them. They become emotionally invested in each other. Their deeper Self weaves with the other person. Layer by layer, strand by strand, experience by experience, day by day, the relationship is built on realness. It is a spiritual fortress built of strong stuff.
Getting rid of it is extremely difficult.
In the case of the narcissist, all you were to them was an idea, all your relationship with them ever was, was a source of supply. They idealised you, and ‘fell’ for your perfection. They never saw you, or felt you. They projected onto you what they wanted you to be, and interacted with you via that projection.
There were no stakes involved.
The narcissist lives in a fantasy where they are perfect, and others are either perfect, or they are perfect providers. Adulation, attention, sex, resources or anything else the narcissist desires to reinforce their grandiosity.
If your behaviour strays from what the narcissist perceives as perfect, then the projection in their mind flickers. The real you appears momentarily. Worst of all, the real them appears. Without the fantasy, the narcissist is an empty shell. If that empty shell ever breaks, the narcissist is faced with a shame-filled, traumatised, unwanted, petulant child.
They never want to face this reality. So rather than look deeper, they blame you. Whenever the bile in their True Self oozes out, they toss it at you through put-downs, harsh judgements and humiliations. Then, when they can no longer uphold the projection, poof. They disappear.
Like a device in their kitchen, when you stop working for them, they toss you out. Once the illusion bursts, there is nothing left but the real person standing in front of them, whom they have zero interest in.
Intimacy. Vulnerability. Normality. Authenticity. They loathe it all. The narcissist has invested nothing of their True Self. You never existed in their soul as a real person. It was all a ruse.