Though the 1904 St. Louis World’s Fair, the 1906 San Francisco earthquake, and the jailing of Japanese-Americans in World War II all figure prominently in Jane Smiley’s “Private Life,” the title is right for a novel about spouses who grow further apart each year.

Margaret Mayfield, Smiley’s heroine, is 27 — an old maid by the Missouri standards of 1905 — when she marries Capt. Andrew Jackson Jefferson Early, an astronomer who is 11 years her senior and, according to the general estimate (especially his own), very much her superior in wealth and genius.

The marriage has been arranged by their mothers, neither of whom has reason to think she’s sending Margaret on a lifelong vacation. “They had known what marriage was like. They had known what Andrew was like.” And yet “they had colluded” to trap her, each for her own reasons.

Andrew’s mother recognizes how seriously her brilliant but intractable son needs a stabilizing influence. Margaret’s mother considers a disagreeable marriage to a well-off oddball infinitely preferable to impoverished spinsterhood: “Romance, she’d said, was always the first act of a tragedy.”

If Smiley weren’t such a famous chameleon it would be hard to believe that these plain-speaking Missourians come from the same pen that gave us the busy bunny rabbits of the randy “Ten Days in the Hills” three years ago (or the Shakespearean Iowans of the Pulitzer Prize-winning “A Thousand Acres” in 1991). Sex gets discussed in “Private Life” about as much as these straitlaced Midwesterners would talk it over with each other.

And yet Smiley ably dissects the sexual dissatisfactions of the Earlys’ marriage, before sex disappears from it altogether. For a man with so much drive, Andrew has a remarkably flaccid libido. He’s an unusual character in fiction: a dedicated scientist whose ideas are flat wrong.

At first Margaret believes him to be the genius he considers himself; it takes her years to recognize him for what he is, “and she did it all at once, as if he had turned into a brick and fallen into her lap — who he was was that solid and permanent for her — he was a fool.”

His closest literary equivalent is Mr. Casaubon in George Eliot’s masterpiece of conjugal suffocation, “Middlemarch.” But Margaret doesn’t suffer with quite the same intensity that the idealistic Dorothea Brooke does.

She is in fact rather ordinary, as Andrew has no qualms pointing out to her — “but there is a perfect balance between your womanly nature and your entirely acceptable level of intellect, my dear.”

Though “Private Life” tells a chilling and demoralizing tale, that isn’t at all how it reads. On the contrary, it’s quietly absorbing, because we observe the marriage through Margaret’s eyes, and Margaret is such a docile being, so bound by the prejudices of her era, that the scales don’t fall from her eyes until late in her life.

The rancor that accrues like a suddenly discovered nest of termites in the book’s final pages is almost as startling to the reader as it is to her. Smiley has laid the way for it plausibly and subtly, beginning with her ironic epigraph, from a 1935 novel by Rose Wilder Lane: “In those days all stories ended with the wedding.”

It isn’t the only way she hints that on the day in 1942 when we leave Margaret, at the age of 63, in the bitter flush of a spousal rage it has taken her 36 years to fully feel, her story may be just beginning.