Bookbag: "She had registered as a Democrat, figuring he would never be the wiser."

From Frances Costikyan's "The Captain in the Election District," published in her husband's Behind Closed Doors: Politics in the Public Interest:

We have often unwittingly betrayed husbands and wives politically to each other. I remember one young bride who had married a very proper, Brooks-Brothers-suited advertising man who hoped to rise in his Republican-oriented agency. She had wanted to retain a little of her past, so had registered as a Democrat, figuring he would never be the wiser. Of course, I had no idea of this situation when I rang the bell and asked for her. (My records told me the husband was a Republican, but many families are split politically, and we cannot stay away from all of them.) Her secret was soon out, and there was hell to pay.

The story takes place in the early 1960's, so anyone not already imagining the husband as a Mad Men character is welcome to do so.