Why did the USSR leave Afghanistan? What made the Trump administration ponder upon withdrawing all of their resources from the Place of Graveyard of Empires? One thing is for sure that Afghanistan is also the Graveyard of Peace as well. There is no doubt about what is happening in Afghanistan and the way it is happening. However, this question will always build curiosity about what led a Great Power of modern times to get slayed and butchered every time. The simple answer to such a question is Great Power Fatigue which gets masked through these powerful countries' narratives provided by their privileged executives. Let's understand this concept from its grassroots level. 

Great Power Fatigue, in layman terms, is like the change in the mindset that compels even the biggest torments present in the international system to change their policy. Consider it with an example. Many of us might have remembered what Mahendra Singh Dhoni was in the initial days of his career. MSD displayed a sense of power strokes every time he was there on the crease. But that attitude changed with time and with him getting more responsibilities. One can witness many innings of the same personality where he had a more defensive approach (Note: Such example should not be used in writing answers as it was merely for explanation). Several reasons or factors changed the mindset and influenced this identity to take a defensive side rather than aggressive. The same applies to the case of countries. 

Now, the big question comes whether the British leaving India is an example of Great Power Fatigue? Why? Some may say that Britain was a Great Power during the time of the cold war. Well, it doesn't apply if there is a talk on imperialism and colonialism. Colonialism keeps a different angle where there is a sense of Whiteman's Burden and administrating the colonies come into the play. Unlike Great Power Fatigue, this subject may lose colonies if there is a risk of severe revolutions or these colonists becoming weaker in terms of economic, social, and other facets. The national movement in India, along with the Indian Navy and Air Force mutiny, opened the eyes of Britishers and made them understand to exit the subcontinent at the earliest to avoid further dent. 

But is this Afghanistan problem since 1979 a newer concept? Not at all. Don't forget that Richard Nixon had to withdraw US forces from Vietnam. Then, remember the instance of war fought in Egypt in 1956, which sent a huge blow to the reputation of the UK (Watch: The Crown Web series). However, before passing such statements, it is also important to understand that such wars brought huge financial stress on every Great Power, which is not easy to sustain. Apart from this, the death of several military soldiers also creates hew and cry in these countries, which compel the Government to withdraw the forces.