what do you do? as time goes on you will find that it is impossible to trust anyone. is this what you want to hear most likely not but the hard truth is that is the way life is. people lie to you and themselves everyday, most don't even know that they are lying anymore because they do it so often. don't get me wrong i am just as guilty as the next i will not be so bold as to not include myself.
the longer i am around the more i distrust humans in general. we are taught to lie almost from the time we are taught to speak. how can people trust each other when most don't trust themselves. your family lie to you everyday as do your friends and coworkers, it is just what happens. no matter a friend, family, or someone that says they love you, you can never really trust them because given time the will prove to you that you shouldn't have.
don't mean to take away your hope but as it has already been said every time you really try to open up and trust someone you will be shit on. just a guess here but maybe the reason it is bothering you so much is unlike most of the masses out there you understand that you shouldn't intentional give your word when you know that you can't keep it. most no longer care to even think about that it is just something they do every day with out thought.