The Winding Stair by A.E.W. Mason

Gerard de Montignac had never been so thoroughly startled and surprised in his life. But he was angrily conscious of an emotion far keener than his surprise. He was jealous. Jealousy overmastered the shock of wonder, stabbed him through and left him aching. Marguerite Lambert, the girl of the Villa Iris, so politely difficult! And Paul Ravenel, the man without passion! Why, his brother officers used to laugh at him openly-nay, almost sneered at him and made a butt of him-because of his coldness; and he, indifferent to their laughter, had just laughed back and gone his way. Well, he could afford to, it seemed, since he was here, and for two years had been here, hidden quite away from the world with Marguerite Lambert.

They had stolen a march upon their friends, the pair of them, they had tricked them-yes, that was the exact right word-tricked them, even as they had just tried to trick him, she with her Oriental abandonment to grief-little "animal," as he had called her in his thoughts-he stretched out on a knob of rock above a precipice in a pose of death! Gerard was in an ugly mood, and he spoke out his thought in a blaze of scorn.