Algorithm which runs in brain of every girls !

while(girl is unmarried)

 best_friend=friends.pop()
 
 if best_friend is better than boyfriend //better contains (richer,taller,handsome,owns better vehicle,caring etc)
  temp =boyfriend
  boyfriend = best_friend
  free(temp)
 end
 
 for(i=0;i< depends on mood of girl ; i++)
  friend =select(one candidate friend from corpus of eligible males)
  friends.push(friend)
 end
 
end

Dedicated to XX chromosomes !!