The lovers
From back cover Del Ray paperback March 1980:

Escaping the religious tyranny of a 31st-century Earth by a fluke assignment to the planet of Ozagen, linguist Hal Yarrow found that the worst of Earth had followed him -- Pornsen, his personal Guardian Angel, vigilant for any evidence of sin or wrong thinking.

Conditioned by a lifetime of submissions, Yarrow would have accepted Pornsen's constant spying as an unpleasant necessity and lost himself in the study of the language of Ozagen's intelligent dominant race, the Wogglebugs... but then he found Jeanette, a not-quite-human fugitive, hiding in ancient ruins built by humanoids long vanished from the planet.

For a believer like Yarrow, unconsecrated contact with any female was forbidden -- and love for an alien was unthinkable.  But to Yarrow, in every way that counted, Jeanette was warmly and bountifully human!
Science fiction
Philip José Farmer
Philip José Farmer was an American author, principally known for his award-winning science fiction and fantasy novels and short stories.

Farmer is best known for his sequences of novel — especially the World of Tiers (1965–93) and Riverworld (1971–83) series. He is noted for the pioneering use of sexual and religious themes in his work, his fascination for — and reworking of — the lore of celebrated pulp heroes, and occasional tongue-in-cheek pseudonymous works written as if by fictional characters.

Philip José Farmer is also well known for remixing classic fictional characters, worlds, and both real and fake authors. This is epitomized with his Wold Newton family group of books that tie all classic fictional characters together as real people and blood relatives resulting from an alien conspiracy; his works such as The Other Log of Phileas Fogg and Doc Savage: His Apocalyptic Life make Farmer the ultimate grandfather of the modern literary mashup. - Wikipedia