Of Human Bondage by William Somerset Maugham

Philip, in return for Griffiths' confidences, had told him the details of his own complicated amours, and on Sunday morning, after breakfast when they sat by the fire in their dressing-gowns and smoked, he recounted the scene of the previous day. Griffiths congratulated him because he had got out of his difficulties so easily.

"It's the simplest thing in the world to have an affair with a woman," he remarked sententiously, "but it's a devil of a nuisance to get out of it."