Theodor Fontane wrote his novel in 1894-5 and it was first serialised in Deutsche Rundshau https://en.wikipedia.org/wiki/Deutsche_Rundschau and appeared as a novel ln book form in 1896. So far, I have only been able to read it in German in an abridged but excellent edition published by ELi Lektueren. It is a fascinating novel which treats with sensitivity the downfall of a young and imaginative girl, a “Naturkind” subject to the stifling and formal Prussian society. It also deals with various other themes and feelings which are discussed at length at https://de.wikipedia.org/wiki/Effi_Briest

There are also interesting film clips on You Tube. The plot is explained in 11 minutes at at

and the clip, giving some feeling of Fassbinder’s extraordinary film may be found st

Just as the book echoes with comparisons to Emma Bovary (1857) and with Anna Karennina(1877) in its poetic realism so the filming by Fassbinder in black and white has dream resonances that makes the whole film so evocative. It is not surprising that the filming took some two years nor that Hanna Schygulla.