So difficult

I have been teaching at my particular school for 2 years but suddenly I am very very unhappy there.  I am not unhappy with the students.  They are the best!  I have been so upset at some of my colleagues.  They are so AMERICAN that it makes me sick!  My best colleagues are the ones from other countries.  Ever since I lived in other countries and then came back to America, I suddenly am unable to make friends with Americans.  All of my friends are mostly from other countries.