My ex-girlfriend suffered from severe anxiety disorder.
Anxiety can be very debilitating. 
It was. She would often have significant feelings of anxiety and fear. It really was the cause of the breakdown in our relationship.
That's too bad. The fear can be quite often very hard to overcome even if it seems to be irrational
It was. She was inclined towards socal inhibition and would have difficulty holding down a job or even leaving the house because she wanted to avoid social situations.
So it may have been a touch of agoraphobia as well?
Agoraphobia
Agoraphobia is an anxiety disorder characterized by symptoms of anxiety in situations where the person perceives their environment to be unsafe with no easy way to escape. These situations can include open spaces, public transit, shopping centers, or simply being outside their home. Being in these situations may result in a panic attack. The symptoms occur nearly every time the situation is encountered and last for more than six months. Those affected will go to great lengths to avoid these situations. In severe cases people may become completely unable to
from the Ancient Greek term "Agora" or Marketplace, while social anxiety disorder is an anxiety disorder characterized by a significant amount of fear in one or more social situations. Such fears can be very debilitating in themselves, and in addition patients often worry about showing anxiety and losing control in public.
Medical uses Post-traumatic stress disorder.
Virtual reality exposure (VRE) therapy is a modern but effective treatment of post-traumatic stress disorder (PTSD). This method was tested on several active duty Army soldiers,