I don't know if it's social anxiety or another factor, but I took a very long time to open up my shell. For most of my life, I've built a small group of tight friends around me. People who I connected with, and stuck with them through thick and thin. It's not always been the best decision at times, as relationships and people change and connections go toxic.
I think a great deal of it comes down to fear. Fear of stepped outside of my comfort zone, dealing with the world beyond the safe places I build for myself. Those places, those people, are the only places where I feel like I can be myself. Everywhere else, I feel like I'm wearing a costume. That the me I show the world. The more I've been able to come out of that shell, there are some things that change; I've built more of those costumes, the faces that show only a facet of who I am. But it's still a role, a costume I wear to try and insulate myself from the world.