To be useful, my friends list needs to be focused. So, I prune mine regularly. The very act of cleaning it forces me to consider what each person means to me and sometimes prompts me to re-establish contact with a neglected friend. I admit to feeling unhappy sometimes when I am defriended, so I try to be sensitive when defriending others. I consider the depth of the friendship, the length of time without contact, and the pleasure, if any, that the friendship brings me. For uncomplicated situations where I perhaps met the person once, no contact in three months is enough to take them off my list. If the friendship meant something to me but now is dead or unpleasant, I sometimes send a polite note at the time I defriend. I try not to burn any bridges.