In countries where there is no marriage, there is no duty between husband and wife; when marriage comes, husband and wife live together on account of attachment; and that kind of living together becomes settled after generations; and when it becomes so settled, it becomes a duty.
At the beginning of a marriage ask yourself whether this woman will be interesting to talk to from now until old age. Everything else in marriage is transitory: most of the time is spent in conversation.
Constancy has nothing virtuous in itself, independently of the pleasure it confers, and partakes of the temporizing spirit of vice in proportion as it endures tamely moral defects of magnitude in the object of its indiscreet choice.