Was the Cold War inevitable?
Historians do not like to say that anything is inevitable. They prefer to emphasize contingency and human agency in historical developments. In the case of the Cold War, however, it is certainly the case that conditions in the aftermath of World War II, combined with the very different ideological positions of the two nations, made some form of conflict very likely. The Soviet Union under Josef Stalin had a strong motive to extend its influence into Eastern Europe, and the United States had many reasons to view Stalin's actions as aggressive and expansionist in nature.
There is simply no way to know, without proceeding into speculative counterfactuals, what could have happened in the wake of World War II if the United States and Soviet Union had acted differently. What is clear is that by the late 1940s, both sides were anxious to avoid conflict while not ceding important diplomatic victories to the other side, especially in Europe. In Berlin, for example, when the Soviet Union tested the resolve of the United States by blockading the city, the United States and Great Britain responded with massive airlifts, a way to keep the city supplied without provoking open conflict by attempting to breach the blockade on the ground. Even as the Cold War intensified and spread, both sides chose restrained conflict, even financing proxy armies in the postcolonial conflicts around the developed world.
This pattern of provocation followed by restraint, (or, in the notable case of the Cuban Missile Crisis, backpedaling) would characterize the entire conflict. In fact, historians have recently argued that the Cold War is best understood as a system of international relations that preserved a measure of stability in the post World War II world, suggesting, in other words, that the outbreak of the Cold War was by no means the worst case scenario after World War II. So perhaps the best way to think about the inevitability of the Cold War is to say that some form of conflict was very likely, but it didn't necessarily have to be "cold."