From Stumbling on Happiness:
"You've probably noticed that with the exception of almost no one, nobody picks friends and lovers by random sampling....
...we are surrounded by people who like us, and people who are like us. It isn't surprising, then, that when we turn to the people we know for advice and opinions, they tend to confirm our favoured conclusions - either because they share them or because they don't want to hurt our feelings by telling us otherwise."

So true. Sometimes if friends do not confirm the favoured conslusions, they don't remain favoured anymore.