FRIENDS issue

it's hard to become a good friend yourself...ppl say in order to have a good fren, become a good fren first....what will you do when your fren is constantly doing sumthing which bothering you a lot?what will you do when you know others are feeling the same annoying feeling upon your good friend just like you did?shall i just talking behind her back together with the majority?or shall i tell my good fren the real problem that arises?or shall i keep quiet to pretend that i own ignorance?maybe backstabbing is easier than truthtelling...truthtelling requires courage and taking risk of being hated by your good fren,while backstabbing does not need them....well, for me...i choose truthtelling...even if i have to face the risk of losing a good fren.....