Can Monogamy Ruin A Marriage?

In one case, probably:

The marriage was ruined, for example, because the partners were so dead to each other erotically that even though their marriage worked really well in other dimensions, as a Platonic marriage, a friendship, and a stable, co-parenting arrangement, the spouses saw no path forward. The lifelong monogamy imperative of marriage that they didn’t want to abandon but couldn’t live with maneuvered them into a box. They couldn’t be married, monogamous, sane, and fully human all at once. So rather than live sexlessly monogamous, they divorced. … The wife wasn’t happier, post-divorce. In that sense, the divorce didn’t “work” any better than the other bad alternatives.

It caused bitterness with the children toward the father, and the wife toward the husband. The husband did enjoy a life that was more of his design and to his taste, but at the cost of his marriage and family. You can conclude that the husband was a bad person in a good institution of (monogamous) marriage. Or you can conclude he was a good person struggling with, if not a “bad” institution, then at least a Procrustean one.