Friends or Lovers...

I just finished watching episodes of Sex and the City. It made me think about friends who are married or with a boyfriend. Somewhere, somehow no matter how good friends you were, when it comes to choosing between hangings out with your best friend or love one. It seem love one is much more important. Aren't friends suppose to be friends forever? We are supposed to shared our sorrow and happiness together now and forever. What happen to the invincible commitment that we commit to when we said we will be friend forever?