High Wizard dabbles in what can threaten his marriage

An astute summoning wizard who is in a high official position, and married to a woman of important, influential lineage, with culture and relevant education, brings in a superior being, somewhat unexpectedly but not entirely. He wants the summoned being to perform a quest that would be desirable. However, the being learns of the summoner's wife, and goes to meet her, and he then would seduce her. She might turn from her husband to be with him.

This all happens in a pre-industrial setting, where wizards can be appointed to important positions. Scientists here are finding things out with experiments that show them just what this world is like. It is a different world, with some creatures that are different, and some substances are unique there. All the metal is exotic metal, mostly megamite, and there is still a much rarer and much more valuable exotic metal. And there are gems, clear gems worth a good deal, and powerful glowing gems. And here there is such power that can open portals to places beyond this world where other beings dwell.