Excellent question. This is something that I'm often aware of. It's because I so often feel almost unbearably vulnerable. I deal with it in my own very personal way, and I'm afraid this usually involves detaching from others, which I feel bad about but I don't really know how to "process" things any other way. Other times I feel safe and then I let loose with more demonstrative displays of affection. Trust is very hard to come by when you take it all in in such a personal way.