Excerpt from a Bernard Shaw letter to his mistress (under the guise of being his wife.)

The present case is a specially difficult and dangerous one, for my husband is not a common man; if you become at all intimate with him he would become a necessity of life to you; and then the inevitable parting would cost you more suffering that it can now. I could not trust him to keep you at a distance: he is quite friendly and sympathetic with everybody, from dogs and cats to dukes and duchesses, and none of them can imagine that his universal friendliness is not a special regard for them. He has already allowed you to become far more attached to him than he should; and I do not intend to let you drift any further into an impossible situation.