Wall Breaking

I really love times when I meet new people and automatically there is that "click" that happens. I often wonder if it is because I find people like me who open up so quickly. I love when I find that. I feel that life is too short to have surface level friendships. Why should we waste so much time getting to know someone only to put up walls?? I can totally tell when someone puts up a wall with me and it causes me to think that I have done something to make them place that wall there. I realize that many people like keeping distance with people and don't like sharing every particular part of their lives with others, but I often wonder why not? Is it a trust issue? Do you fear that they will use that information as blackmail to you later? Do you reserve these types of stories for whomever you will marry one day? What is the reason behind this? IS there is a reason? I'm interested and intrigued by why people like surrounding walls around them. Maybe I have a lesson to learn in needing to put up more. Maybe there is a legit reason as to why someone should "guard" themselves. I'm not speaking of guarding hearts here, I'm just focusing on sharing one's life with others. Your hurts, your hang-ups, what makes you tick, how you are most encouraged, etc.