It is common to confuse emotional restraint with an outright lack of emotion: The colleague who does not complain, the friend who hides their experiences from others, or even the partner who does not react strongly to any sort of issue may all be regarded as someone who is emotionally stoic, detached, and even difficult to understand.
There is another perspective on the matter that can be drawn from psychology. In attachment theory, emotion regulation studies, and even within developmental psychology, a constant pattern may suggest a different interpretation. Those individuals whom one regards as being emotionally detached from the world around them may, in reality, experience things just as deeply as anyone else but have learned that doing so poses various dangers.