Fiction -- briefly; A German Love Story, by Rolf Hochhuth. Translated by John Brownjohn. Boston: Little, Brown. $10.95.

Hochhuth's title is ironic. Using the World War II love affair of a German woman and a Polish POW as a focus, he examines the temporary German insanity -- Naziism -- which made a state crime even of love.

Mixing fiction, reportage, documentary excerpts, and editorial musings, Hochhuth, who was born in Germany and is now a Swiss citizen, argues that Nazism was a triumph of emotion over reason, a season of self-deception.

Hochhuth, who has written "The Deputy" and four other plays, is interested here in the behavior of the ordinary Germans, those who emerged from the war as if from nightmare, unable to believe or admit their part in the horrors that had become their nation's history, their own pasts. He shows these citizens mechanically, against their own sympathies and instincts, playing out the tragic consequences of the (sometimes graphically described) affair between Pauline Krop and the POW laborer assigned to her grocery store.

Writing more of a tract than novel, Hochhuth's mixing of fact, fiction, and editorial comment diminishes the clarity, coherence, and general persuasiveness of each. The central thesis, however, that the citizens of Hitler's Germany were not the first to fall victim to such a delusion, and its implied correlative that each of us must look toour own integrity to ensure our not becoming the next, is strong enough to lend the work a chilling relevance and power.