Views on whether or not tragedy provides a fulfilling end to a work have changed over the centuries and it has slipped in and out of popularity in contemporary works of a given period. Great literary classics, such as Romeo and Juliet, have always been respected regardless of prevailing literary modes. Nevertheless, the presence of tragedy in literature has fluctuated from its beginning in Ancient Greece, then to its obvious comeback in Shakespeare's day, as well as to the present seeming revival in modern literature. This therefore suggests changing attitudes towards literary tragedy.
Tragedy should be considered just as a fulfilling ending as a happy one, so when and why did popularity for tragedy change over the centuries?
Prompted by Rand al'Thor's comment