Who is to say exactly what is the correct emotional response to an event? What is the accepted emotion-spectrum for the event(s)? Who decides that spectrum? Who calculates the multitude of conditional probabilities and if-then statements to determine what is the socially(and possibly therefore medically) acceptable response to an event or an amalgamation of events? The current social zeitgeist? Medical professionals? It seems to be reduced to observable behavior and whether or not that observable behavior becomes an abnormal behavior where the definition of that abnormal behavior can fluctuate depending on one's native culture, the culture and/or society they currently inhabit, and more importantly the time period. It seems to me that depending on where you are in the world and the time period, one emotional behavior is acceptable at point (a,b) and deemed abnormal at point (c,d), where "a" and "c" are location and "b" and "d" are time period.

All that said, I do think there are universal and timeless emotional states that may or may not stem from an environmental factor, in some form, that are and can promote states of psychological/physiological "un-health." Also, mass hysteria seems to be a thing so just because an emotion-behavior is not abnormal within a large group doesn't necessarily mean that it's not unhealthy. There seems to need to be some form of observing nuance to determine the "correct" emotion-behavior.