You can find ideas regarding to the Cold War here.
The idea from this link is that it demonstrates notions of how this rivalry between the USA and USSR began from way back in the past, the event where the Bolsheviks had taken power in the Russian Revolution. The USA disliked the idea of the Bolsheviks acting as the new government. So some may say that this disdain of the Bolsheviks from the USA may have been the trigger of rivalry between the USSR and USA. However, if it wasn’t for the Revolution to take place, maybe the Cold War wouldn’t have happened as Communism would have not began from that point onward.
From this website, it presents us knowledge about why the rivalry began to become bitter between the two Superpowers. The USA had knowledge about creating the nuclear bomb and yet didn’t share this information with the USSR during the war. This had showed the unwillingness of USA not keen on preventing the pressure off of Soviets by the Germans in the Second Front. It may have been that USA was in fear that if the USSR had such knowledge of the nuclear bomb, it would have been a backfire to them, as we know that Communism didn’t work with Capitalism, so we wouldn’t know how the USSR would act once they had the nuclear weapons in their hands.
Some may even argue that it was Truman that led to the Cold War due to his strong Anti-Communist belief, as he made a’ get tough’ act against the Communist. His policy of Containment was the problem to the Communist, since he wanted to spread democracy around Europe, which went against what Stalin had wanted. From this, there were suspicions upon each other, leading to the breakdown of their alliance as they didn’t have any common enemy left. What they had in common was to spread their ideologies, escalating to the Cold War of the two Superpowers.