For Christians, the reason why it is ordinarily assumed that...

For Christians, the reason why it is ordinarily assumed that a marriage will go on "till death do us part" has been that this advanced lesson in Charity which marriage opens into is a long, a difficult one, and the life span that my spouse and I are allowed will certainly not be nearly long enough to finish the lesson... I will have as much as I can do to learn this advanced lesson well with one other person; a harem will only confuse my efforts.