The Combined Maze by May Sinclair

That was how they kept it up together.

Not that Mrs. Ransome was conscious of keeping it up, of ministering to an illusion as monstrous as it was absurd. She had married Mr. Ransome, believing with a final and absolute conviction in his wisdom and his goodness. What she was keeping up had kept up for twenty-two years, and would keep up forever, was the attitude of her undying youth. It was its triumph over life itself.