Narcissists experience jealousy in relationships uniquely, and is driven by how they see and internalise the people in their lives.
In short, whether a narcissist experiences jealousy or not depends on:
How they have classified you.
Where you are in the idealise, devalue and discard cycle.
Narcissists see people in a binary way; a source of supply, or not a source of supply. For those who are a source of supply, you can either be disposable, or coveted.
A coveted source of supply brings the X-factor with them. They are worldly, attractive and emotionally uninvested. They are a prize to be won. And when the narcissist wins such a person, they covet them — especially because the narcissist knows this person could leave them at any time. This is where the narcissist’s jealousy comes out.
The coveted sources also represent something deeper for the narcissist. Because the coveted supply is an unattainable, more powerful figure ‘up there’, they resonate with the narcissist’s unloving parent. As a result, the parent archetype activates in the narcissist’s mind, and the narcissist regresses to the childhood jealousy they experienced with their original parents.
However, if you do not fit this mould, then you become disposable. As long as you provide sex, attention, services and consistency, they will use you for narcissistic supply. But when you are not around, they could care less who you are seeing or attracted to. If you don’t come back, and they still have supply elsewhere, they will barely think of you.
The one exception to the coveted supply jealousy is the devalue/discard phase. If you betray the narcissist and hurt their grandiosity enough, they will surgically cut you off and never want to see you again. Then, again, they could care less who you are with.