i think its part of our condition , ptsd certainly becomes an illness of isolation. I find that being alone can certainly intensify the symptoms, and if your not careful it can also make dealing with them a lot harder.
I remember listening to a marriage counsellor being interviewed, who had been doing it for decades and they asked him what he thought was the root cause of marital conflict. He stated it was loneliness and as humans we all suffer from loneliness, but the trouble comes when we expect others to alleviate it, and we must address it from within.
I do suffer from loneliness from time to time , but at the same time i am reasonably comfortable in my own skin and keep myself occupied for a good part of the time, i am very aware how much the symptoms can intensify and when this happens i tend to go for a drive or do something to break the cycle, otherwise it becomes a vicious and self repeating