Along similar lines to the last, to be honest.
I guess sometimes there is no translation, people do or say things that seem uncharacteristic, and even if you think you know them inside out, even if you think you're close enough to be, say, sisters...they can still surprise you and hurt you.
Maybe I have too much blind faith in humanity but part of me refuses to believe that somebody that close to you would do something, knowing that it will not only hurt and confuse you, but will jeopardise your friendship.
Maybe I'm just disillusioned.