Why I Have A Wall..?

My friends say no matter how close someone is to me there’s still a part of me they can never get to. A part that I never let anyone see, or reveal. This part is so hidden that people can never pin point what they think it is. So well concealed they have no idea how to get to it. I was once told that I would be a good at poker because I have a good poker face, I show no specific emotion. I supposedly have this wall that no matter what you do you can never penetrate it or get over it. Irony of the situation is that even I didn’t know I had this wall. I always thought I was quite open with people, when your close to me you know your close to me, you’d never have to doubt that. But somehow it seems even the close ones feel miles apart from me. Always an arms length away. And I can’t help it. To be honest I don’t really know how to explain it or let alone know how it got this way or when. How do I even explain it to myself. I guess I’ve always just been used to being the one who takes care of people. The majority, more or less all my relationships with people consist of me being there the most when people need me, even if they can’t admit it. But whose there for me? I know it sounds weird but although its not intentional, we’ve all had friends which we lean on a bit too much and when its their turn to lean on us we’re far too busy to be there let alone notice. And I guess in that time I learned to lean on myself if that makes sense. Be strong for myself. Be the stronger one out of all my relationships with people. But it doesn’t mean I’m not weak or crumbling inside when things go wrong. It doesn’t mean I don’t need someone to be there for me to make sure I’m ok. I’m just too strong to admit it because I feel like I need to be. I’m so independent I don’t really need looking after but sometimes its what I want and need the most. Does this even make sense why I have a wall?