your teacher is right in his point of view. You are in school and school has the responsibility to teach children and parents expect the school to protect their children as they do. Teacher is doing his/her job to maintain the discipline of school and not to make it a lovers point.
Its not only concerned with you. Imagine if all the students of school start the same thing, then what will happen to the school and teaching? so don't take it personally.
You may be right in your point of view but still you have to maintain the limits till friendship and never do things which which make people around you to have suspension. I am not blaming you for anything but we must do things in limits and always have to take care of our social environment.
there are things which can't be changed like our culture. You or many may have difference of opinion regarding openness but this is what you are, this is where you live.
Things without limit are bound to create trouble.
Take good care smitha