1911 Encyclopædia Britannica/Honeymoon

HONEYMOON, the first month after marriage. Lord Avebury in his Origin of Civilization suggests that the seclusion usually associated with this period is a survival of marriage by capture, and answers to the period during which the husband kept his wife in retirement, to prevent her from appealing to her relatives for release. Others suggest that as the moon commences to wane as soon as it is at its full, so does the mutual affection of the wedded pair, the “honeymoon” (with this derivation) not necessarily referring to any definite period of time.