Actually your jacket is very similar to European jackets from that period . If you look at some of the German aviators jackets from the 1940’s they look very much like yours. So it’s conceivable that your friend picked it up as a souvenir or “liberated “ during the war .No he was not German but did serve in the European theatre. It is the double row of buttons that is confusing. Everything I find for that era has zippers