A co-worker recently intimated to me that she isn't big on befriending people at work. When I asked her why, she said you never really know who you can trust. In her experience, sometimes the last people you would expect to stab you in the back are the ones who do. I couldn't refute what she was saying because I have experienced it myself. Some people pretend to be nice -- to like you, to be your friend -- but when the opportunity arises, they sell you out without blinking, wholly inconsiderate of your feelings. Does this mean we should be cynical with everyone we come across? Of course not. What it means is that you shouldn't confide in them until you know for sure that they're trustworthy, and that includes: Not divulging information about your relationships, finances, or other personal matters that they can then use against you if things go sour. Not doing favors for them (at least not constantly) before you know whether they've got your back ...