IMHO it began earlier with WWI. Europe went from a largely agrarian region in 1815 to prosperous industrial societies in 1914. Science and industry revolutionized in a century where there was no "world" war. The Europeans thought they had it all figured out.
Then came the shock that they fell into a world war over, essentially, nothing. They created a system of international institutions, treaties and arms limitations to try to see that it wouldn't happen again. The Oxford Union swore never to fight for King and Country under any circumstances.
Despite the evidence in their face of evil and aggressive fascist states, they still thought they could have "peace in our time." The British and French fought WWII only because Hitler finally left them no choice. The Russians fought because, well, they were invaded. So, Europe was indeed traumatized, I would agree. After a century of relative peace, two world wars from 1914 to 1945 with only a brief intermission in between.
I agree with you that renewed war is inevitable. The history of mankind yields no other answer. But Western elites, people like Obama, think you can have peace by refusing to fight. And Europeans have way to much faith in the EU and UN to maintain peace. The situation bears much resemblance to the pre-WWII era and, as you suggest, soon no one will be left alive who witnessed the horrors of WWII.
Right on the mark
I agree completely
One other note. The 20th century was to a great extent about the ending of monarchies. Some survived, ie Arabia but most ended. The turmoil can also be attributed to the search for new government