Why are friends such back stabbers?

Why are friends such back stabbers?
I would not generalize that to all friends. Still, at times some friends do let us down. Relationships are based on trust, and that only develops over a period of time through a variety of situations and circumstances. However, we as humans are unpredictable and often fall short of doing the right thing, at the right time, for the right reasons. If you ask why, it's because we are unique yet susceptible to reactions that are facilitated by one out of a hundred reasons, or a combination of all of them. Sometimes we just live in our own little bubble, and do not realize how we affect others by what we do, or don't do. All of us need to move out of out self centeredness and think about others before we act. Because this has happened to you, see that you do not do it to others. In this way you have learned something valuable.