Faithlessness and marriage

I know a couple who have cohabitated for years, had a baby together, and finally married last year. This past week, she left him. She didn't so much break up with him as she dismissed him. Just didn't dig being a wife anymore, it seems. He's crushed, on a roller-coaster of emotions right now. And these aren't kids, they are staring middle-age in the face. You never know what's going on in other people's families, I guess. But I hate the sight of solemn relationships being abused, being entered with a giggle and exited with a shrug.

Have some quotes:

Alas! how many who have been confided in for years, have yet suddenly proved faithless to the trust reposed in them.
-- Mrs. H. Buckner

Faithlessness is one of the most pernicious sores of our social life; it contaminates all it touches, and spreads disorder, ruin, and despair in the path of those who have loved, trusted, and been betrayed.
--James Ellis

He lives in a serial non-pledged monogamy, in ad-lib cohabitation. This is preceded by no awe-provoking exchange of oaths, or reminder of his (now legal) duties.

When he tires, and eventually marries, the ceremony will be understood as supererogatory--has he not engaged in cohabitation several times before? He knows how to live with woman, he has done it many times.

The awesomeness of an oath, and the meaning of his signature on a legal document committing him to various responsibilities, will occur to him--though only at the *end* of his marriage. They in their totality are known as "divorce", which has, in our day, replaced marriage as the culturally determined ritual signifying "leaving home".

The ceremony of beginning one's new home, of separating from one's parents, originally ending in marriage, with desire and joy, has been replaced and is now attended by rancor and shock: the community has finally insisted upon its rights.
-- David Mamet, The Secret Knowledge, 2011