I think I'm with Scottish Player and Travis88 on this. It isn't being single, it is the never part of it, in my case never having had a boyfriend. There are so many things about this that depress me.
Partly it just really pisses me off when people who are in relationships say "oh but you have so much more independence when you're single, you have so much more freedom when you don't have children etc etc". That is true, but they have made the choice to be in a relationship/ have children etc. I haven't made the choice to be single. It isn't a case of not having met the right person or needing to look harder. It is about being unable to do this.
Partly it is simply not knowing what it might be like. Not everybody finds someone and gets married and lives happily ever after (ok, nobody does really), but I don't like the thought of never knowing and never experiencing relationships for myself.
Partly it is that I can't bear the thought of people knowing that I have never had a relationship. I was pretty embarrassed about it when I was 21. At 33, the thought of people finding out that I have never had a relationship now has its own separate phobia category (as opposed to the fear of interacting with single men which has prevented me having relationships). Funnily enough, finding out that social phobia exists and I have it has actually helped this a bit, because before I couldn't explain it, even to myself. I thought I was a freak and knew there as something wrong but couldn't understand or explain it. Now at least I know. (This is encouraging, it is progress).
Partly it is that I hate lying and I am a very honest person, but I have felt that I had to lie about relationships (mostly by omission, I don't invent boyfriends but I don't say anything on the subject). So I feel like I'm carrying around a dark secret and having secrets like that is isolating. When people make comments that assume I have had relationships I feel like a fake.
Partly, it is that at my age, even if I can get over the worst of my anxiety, I have left things a little bit late. If I have children, it will only be if I find the right man to have children with, I'm not doing it on my own. But time is slipping away, and I still have to get over enough of the social phobia to be able to cope, find the right man, and then start thinking about whether I want children with him. I know women who have had children in their late 30s and it is so much tougher than for younger women.
I know that even if (sorry WHEN) I get past the social phobia, life will not magically become rosy and effortless. That would just be setting myself up for disappointment. But even the improvements I have made so far show me that (a) I have been wasting a lot of time and energy being miserable and afraid, and (b) the efforts I put into getting over social phobia are totally worth it. (Sorry couldn't end on a pessimistic note - I'm a determined optimist despite everything.)