I totally understand what you mean. I've been told by people that I am the hardest person to get to know that they have ever met. I'm always asking people a hundred questions about themselves but when the tables are turned and they're asking me questions it's hard to get answers out of me. I'm afraid to let anyone in for fear of being hurt. That's especially true since I was diagnosed as bipolar. As a result, I have lots of acquantinces but few actual close friends. I get really lonely but I can't bring myself to let those walls come down.