Lets say they are doing something wrong... they know it... even know why... but they won't stop. You've listened, explained, coached, guided, supported... they get counseling even and that has not progressed them. The wrong they do can "blow up" and hurt themselves or others but they are unable to stop as yet. In the meantime, the drama continues as they play out to you the drama of their daily life.
They can be a wonderful person in some areas, but poison in others.
Do you abandon such friends, when?
Example: Adolph loves his girlfriend and is wonderful to his favorite dog. But Adolph is hurting others via his policies, based upon his fears.
Bob is lying to his girlfriend... he knows it's wrong, and knows why he does it... but keeps doing it due to fear of the consequences. The result is emotional drama as his girlfriend is confused and frustrated.