Driving Wedges

"Orbiting" around another person and attaching one's self to another person whom one admires or wants to be associated with is a common trait of codependency. This WITH Narcissism or certain other disorders can mean that the person wants to be the other person's NUMBER ONE "fan", or "buddy", or groupie, which means they ENVY anyone close to the person. ESPECIALLY their romantic partner, their child, or close platonic friend.
In less severe, more common cases, the codependent person will do things like loosely gossip about their fixation's partner, child, or close friends. They might claim ownership of "understanding" their fixation MORE THAN other people, They may feel that there is a special connection between them, and the other person just doesn't know it yet (that one is pretty common in healthy humans too, especially youths). But they don't usually make a serious impact, or try to make one. They are probably somewhat aware that they have a bit of a fixation, and that those in relationships with the person deserve their basic respect.

In more severe cases, those orbiting the person will try to drive wedges between their fixation and their close relationships. Their goal is to separate their fixation from the other people close to them in their lives, so THEY can be the person (or people) closest to the "admired" person.

Methods and tactics vary, from subtle enticing, such as invitations, business opportunities, tickets to shows or games that DO NOT include the partner/child/close friend (the way people entice a pet with a treat), to snubbing and disdain toward the fixation's significant others/friend, to outright slander and rumor spreading about the fixation's partner/child/friend.
Tactics such as getting the fixation person to "party", drink or do drugs with them are common, especially when the person has slowed down or stopped. Also, flirtation and attempts at seduction are quite common to establish "ownership" over the person. Even setting their fixation up with SOMEONE ELSE, other than their partner, is a known tactic. The goal is not for that new coupling to work out, it's just to get the original pair to break up.

All of these tactics are attempts to break the bond between the person they are fixated on and their significant others/close friend. Then, the codependent Narcissist will feel that they have full access to the person without anyone else "in the way".