Try Signal magazine - published by the Germans during this time. IIRC you will find some ads advising soldiers to avoid fallen or racially impure women. It was distributed to troops throughout occupied Europe and often had pieces on 'local culture'.

do a search for venereal disease pamphlets and posters and shorts that the army produced. Also, there's a bit of a blurb in the book Hitlerland, about Germany in the 1920s and 1930s. It talks about how the Nazis had a very pro-sex view, and their rallies whipped people into a frenzy of lust, with lots of women waiting outside to meet men, and the Nazis trying to de-stigmatize birth outside of wedlock, in order to encourage more births.

It's a rather broad topic. People have literally written doctoral dissertations on this subject.

What specific issues were you interested in? Fraternization between soldiers and local women? Venereal disease? Rape? Prostitution?

Here's an example of a training filmed to teach American soldiers about VD, made by none other than the great director John Ford: https://archive.org/details/SEX.HYGIENE