It seems to me lately that many folks shy away from closeness in friendships. It's interesting b/c it is not likely that they'll pull out the excuse of "I've been hurt before" with friendships, but still they keep some distance emotionally.
One of my good friends is this way. Although she says she cherishes me as one of her best friends (which I do believe as she and I have been friends for a while), even with me and years of warm up, she keeps a protective barrier. This is also one of my friends who does not do well in relationships.
She is a more extreme case but other folks let a few people in but guard themselves from the rest of the world. It is most curious.