Newton's third law

For every action, there is an equal and opposite reaction.

I have heard this hypothesis forwarded before, and it is a compelling theory. I wish you luck in your investigation, and I would love to hear more about this thesis in the future. 

I think there are a few things to keep in mind while working on this thesis:

1) Germany's partition between Soviet and Western powers after the war created an artificial divide within the nation. It would be worth thinking about how this artificial divide emphasized the construction of borders in the minds of German citizens (particularly any that lived around the Berlin Wall). 

2) I have read a few English articles about the anti-nationalist views of several modern German politicians earlier this fall. It might be worth tracing those ideas backwards to see where it originated.

3) Was there any other major refugee Crises that Germany either participated in, or had commentary on. For example, did the civil war in Yugoslavia have any impact on German policy?

These are all questions well worth further examination, but hopefully they offer a good outside perspective of your research. I am not a German historian, however, so I cannot offer any particularly strong primary sources that you can consult. Please let me know if you have any further questions.

The interests of politicians do not always coincide with the interest of the majority of people. There was no referendum in Germany before the slogan "refugees are welcome" was proclaimed. Even if some part of society wanted to deal with past trauma, they were not aware about real volume and externalities - in labor market and personal security.

Look at this picture about the reasons for Brexit. Perhaps this is not only the view of Ben Garrison.

I think past history may well have played a role, but not the main role. Chancellor Merkel's meeting with a young Afghan refugee who broke down in tears and who Merkel tried to comfort, may have had an impact on her own personal views and motives (and Merkel is very important in understanding Germany's choice). But I think other factors were more important: First, Merkel believed that she would manage to get the rest of the EU with her in a refugee redistribution deal. This backfired, though. In the end, Sweden was the only other country that followed Germany's example. As a result, instead of a relatively small, manageable burden for the combined states of the EU, there was a big and unsustainable burden on Germany and Sweden. Second, Germany's labour market is short of labour, so many in the political and economic leadership viewed an influx of well-educated, young Syrian refugees as a potential economic boost.

Good luck with your writing.