Well. my thought on this is clear. Life is meaningless without disappointment. while we journey on,we are bond to face a lot of thing both encouraging and discouraging on our way because those are the event that makes us strong. we can't do without other because they have been in our lives for a particular role(be it short lived or long lived)just like we have our parent. Just like you wrote, not all friend are bad,but if you have an encounter with one, they are there as a lesson while some a reason as said by mother Teresa said.A quote says "if you want to move fast, move alone but if you want to go faryou'll need someone" it'll also be very good/adviceable to scrutinise (check/study)people very well before you allow them in to ones life. Even, some purported good people can turn bad all of a sudden but the best decision is to make the Masteroftheuniverse (God)our best friend in prayersand everything we do. he is the only one who can never turn bad and he always direct the rightandthebestfittedpeople to his children's way.So it is better we <em>trust</em> Godthat even if we lose some good people he'll replace them for us.