Josie,
I think it starts out as a way of protection because we have PTSD and we need to withdraw because the stimulation of normal life is too much for us. It then snowballs and we become worse. We are hyper sensitive to everything. When we walk into a room we know who is unhappy, who is insecure, who's personality we will conflict with and who we feel inadequate around because of social status and other things. Just walking in a room is overwhelming. Not only do we know way too much, but we feel responsible to fix it all because this also protects us from further stress. Fix the problems and alleviate the stress. It's hard to be assertive because we don't want to make waves that would further cause stress.
I am just happy as a clam sitting here with all of you instead. Maybe not healthy, but functional.
Hugs,
MG