I have been around many breeds of dogs, and I have yet to see a breed more sensitive than a Great Dane. They are called the gentle giant for a reason. Boxers are very sensitive to human emotion and children, however at young ages can be quite stubborn. Sometimes you can see a look on their face that looks just like a hard headed teenager.
what you have said is SOOO true! My male Brindle clenches his teeth and his ears go back to his head, when he is refusing to do something for me! It is like dealing with a stubborn teen! lol