Acting passive-aggressive is not something you do very consciously. I must admit I'm guilty of it and if it really comes from fear of embarrassment or making mistakes then that is a real problem.
But I think passive-aggresiveness can also be seen as the result of being unable to vent your anger/frustration. This inability may not always be your own fault. As with the original case of passive-aggressive soldiers, they had no available normal outlet.
If you are in a relationship which you feel you can not break, it is basically the same thing. When you're past the point that venting anger changed things, and now only harms things, passive-aggressiveness is the only road left.
But I think passive-aggresiveness can also be seen as the result of being unable to vent your anger/frustration. This inability may not always be your own fault. As with the original case of passive-aggressive soldiers, they had no available normal outlet.
If you are in a relationship which you feel you can not break, it is basically the same thing. When you're past the point that venting anger changed things, and now only harms things, passive-aggressiveness is the only road left.