Describe how the Cold War ideology that crystallized after WWII changed wartime alliances that had existed during the war.

How the Cold War ideology that crystallized after WWII changed wartime alliances that had existed during the war. I understand how there was a nuclear threat between the US and Russia. The confusion are the other alliances we had during the war. Did we anger other countries due to winning the war? What if anything caused our friendship to change and with whom?