What constitutes a good friendship?

While watching the series of Sex and the City the other day, I began to ponder on past and present friendships that I have embarked on in my own life. Living in New York with substantial careers, the girls of Sex and the City have a strong friendship and connection that is never broken no matter what problems they endure. Is this unbreakable bond realistic in real life? From my own personal experience when it comes to girlfriends i tend to think "QUALITY always outweighs QUANTITY". You can associate yourself with many females from high school to the time you graduate college, but more than likely only a handful of these girls will remain your friend in the end. So why are female friendships so short-term and impractical? Well the first problem in a female friendship occurs once every one's hormones start raging, and females start becoming more concerned about the opposite sex. I myself am guilty of this, leaving a friend aside to hang out with your boyfriend and coming back to the friendship after he breaks your heart. Females tend to be users in a friendship, asking their friends for emotional support then moving on when the negative moments in their life have subsided. Another reason for such fake relations between females is the concept of jealousy. I have lost some friends who seemed to become less interested in me once success and good fortune came my way. These are the friends that hate you when you look pretty and are by your side when your straight broke. They crave your failure and seek your friendship only when your down because it makes them feel better about themselves. Why are females so hard on each other? In the end everything in today's society is about competition, and females will take it upon themselves to knock each other out of the top spot. When embarking on a new friendship its best to watch someone's ways before your call her your "BFF". Just like relationships with men, it's best to take it slow with any new affiliation.