I, too, have difficulty bonding. In watching Star Trek TNG the other day, I heard a quote from Data that pretty much explains my perspective to a T: "As I experience certain sensory input patterns my mental pathways become accustomed to them. The inputs eventually are anticipated and even missed when absent."
I have trouble identifying (or really even 'feeling') emotions, so it's often difficult for me ascertain whether I do indeed 'like' or 'love' a person (as friend or otherwise). I have 5 close friends (if u include siblings) who I genuinely look forward to hanging out with, and enjoy chatting with, even about inane topics, so I classify that as a 'bond'. I have a second tier of friends that I am 'accustomed to', and enjoy talking with them in the hallway at school, but wouldn't be able to hang out with for long durations. But even with good friends I retain a level of detachment--if I were to move, I'd think of them, miss them, but I wouldn't be over distraught. I'm one of those perpetually happy people, who draws pleasure from simple things like nature and smiles.
I've often thought that I just had muted emotions, but I still get furious about some things, saddened by others, and, as I said, I'm usually pretty happy. I think it's 'love', or 'bonding' that I might be incapable of, I just didn't know how to classify it till I saw this thread