Respect and loyalty form the foundation of the instructor/student relationship. It must be mutual and constant. Many things we may not give a second thought to are actually considered to be very disrespectful, and should be avoided.
Earlier tonight, I was contacted by someone who currently trains at another school but was looking to supplement their studies with more realistic self defense training. Upon learning that they were a student elsewhere, I immediately turned them down. If you are a student somewhere, and there is something you have an interest in but are not currently learning, your first responsibility is to talk to your current instructor. Often times, we can accommodate you. I certainly do not teach everything I know within my main program, and many instructors are the same. Perhaps what you're looking to learn is also on the minds of other students in the school, and this "want" can influence your instructor to add an additional class/program, or even offer private training.