ultimately for one central reason--that they have not God in their
lives. I have read as much modern fiction as most people. And while I
have plodded through elaborately told tales of the sufferings of
married people, my amazement has grown that these tales are almost
without exception the stories of people who had no conscious relation
to God. Their authors seem to think it a most interesting thing that
such lives should go wrong, and they base upon that fact the suggestion
that life is essentially a tragic and rather disappointing matter. To
me nothing seems more inevitable and more entirely explicable than that
on such terms life should fail, and should fail alike for the married
and the unmarried. What could be more simple!

The essential greatness of man lies in the fact that he is capable of
fellowship with God. It is in realizing that fellowship that he truly
comes to himself. In nothing less than that can he ultimately find
satisfaction. The reason why all lesser experiences fail him is just
that he was made for something greater still. These lesser experiences
will carry him through the morning of life and past the usual time for
marriage. But later on the unalterable facts about his nature begin to
assert themselves. Though he does not always know it--often indeed does
not know it--he begins to need his God. And till he finds God he is
wrongly related to the whole universe. Though he will generally fight
against it a certain sadness threatens to settle on his spirit. He will
try all the old joys; and though he may pronounce them still good, a
quiet voice within will pronounce them not good enough. He cannot live
even on human love, and a disturbing force will begin to trouble him
even when he is with the wife he has loved so well. And so marriage
begins to fail.

I find the psychologists saying this with their peculiar vocabulary.