What to Do When Your Friends Don't Like Each Other

"Dear Dr. Sala," writes an 8-year-old friend of Guidelines, "my name is Amy and I have a problem with my friends.  Missy won't like me if I like Aimee!  I like both of them but I don't understand!  I don't know what to do!  Could you tell me...?"  Signed, "Amy--your 8-year-old friend."