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
Social inhibition
Social inhibition is a conscious or subconscious avoidance of a situation or social interaction. With a high level of social inhibition, situations are avoided because of the possibility of others disapproving of their feelings or expressions. Social inhibition is related to behavior, appearance, social interactions, or a subject matter for discussion. Related processes that deal with social inhibition are social evaluation concerns, anxiety in social interaction, social avoidance, and withdrawal. Also related are components such as cognitive brain patterns, anxious apprehension during social interactions,
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,