The fourteenth century is described as an age of adversity for many reasons. In this answer I will give you the top three reasons.
First, the plague called Black Death peaked in 1348-1350. Although it is difficult to estimate numbers, the Black Death is estimated to have killed up to fifty percent of the population. Even if we take a more conservative estimate, around thirty percent of the population died. In other words, every third person died. This is simply devastating. It would take the world over a hundred years to regain that population.
Second, there were great problems in one of the most stable institutions of society during this time period - the Church. The great schism took place in 1378 and there were two rival popes, one in Rome and the other in Avignon. This shook the confidence of the people and divided nations.
Finally, there was also the spread of the Ottoman Empire and it threatened the very fabric of the Western world. This was not a false fear, because in 1453, the Ottoman Empire took over one of the greatest cities, Constantinople.