Ludwig is an officer stationed in Italy when Germany occupied it during WWII. He and Fem!Italy meet and despite everything against it (the war, their disapproving families & friends, different social/economic classes, ect) they fall in love. Then as the war progresses they're once again split up. Then years after the war they find each other again...

Bonus: It's not love at first sight for either of them.
Bonus 2: Italy becomes pregnant (when she finds out in relation to the plot is up to you).
Bonus 3: Prussia/Austria is worked in somehow.