Too close for comfort...

I have discovered why I don't have even a few close friends..
I think it is because whenever I do have friends who become slightly close and when I am concerned for them and make the move to say something, however way I say it, sometimes I may be slightly insensitive in my expression because I haven't thought enough of it, or I might be thinking about it too much in one instant and initiating because of adrenaline/impulsive thinking?, or even if I try hard to be sensitive it turns out wrong and I end up hurt.. I try to be nice and I end up getting hurt over small things friends say to me.. Or maybe it's just that I haven't had friends who "speak the truth/rebuke" me unconciously in a long time..
Maybe people do sense that I am sensitive when it comes to those type of things and therefore find it hard to tell me when something is wrong, but I rather they tell me earlier in order to not experience the explosion of emotion that is suppressed.. I do sense it even though people may try to keep it under control.. their facial expressions, the way they say it to someone else and it is said back to me..
it scares me for that moment, and I dwell on it for a period of time and then it slowly leaves me... but it will always linger in the back of my mind..

So what is it? I am trying too hard to make friends, so I push them away and hurt them and myself,.. is that it?
Or I just simply cannot make those kinds of friends because I have not had experiences in early adolescence to teach me How to?
Or because I see the pain that can be caused between friends that are close..and I am scared to experience it...
I can see a theory in this though that relates to a quote "it's better to have loved and lost than to never have loved at all" -- can apply to friendship... having good friends may cause pain but you also receive special "attention" from them..
But sometimes I am just too scared something will happen that will destroy instead of strengthen friendship...