Third wheel.

[hurting300]

Is it realistic that a disordered persons friends may have the same problems as them? Maybe being used by the person in question?

[thisworld]

Sure. Nons relate to pwBPD just like they relate to other Nons and pwBPD can sure do the same. The BPD-NPD dynamic is well-known and other dynamics are very possible, too. My ex triangulated with a long-term ex of his that he keeps pretty close in his life and whom I suspect has NPD - which makes both of them come up with codependent behaviours in this dynamic.

In what way do you think this friend is using the person in question and how is that affecting you?