Elisabeth Celnart, The Gentleman and Lady's Book of Politeness and Propriety of Deportment…
“ The conversation of husband and wife cannot be elegant, and sustained in the same manner that it is in society; it would indeed be superlatively ridiculous that it should not have interruption or relaxation, but it should be free from all impoliteness and indelicacy. If at any time the society of your husband or wife causes you ennui, you ought neither to say so, nor give any suspicion of the cause by abruptly changing the conversation. In all discussions you should watch yourself attentively, lest domestic familiarity raise itself by degrees to the pitch of a quarrel. ”
