4 ideas
Because of hereditary mental deficiency in his own family, his own rules bar him from marrying. He falls in love with Kitty Grammont, an official in his Ministry, and when their marriage comes to light the scandal discredits the Ministry he built.
When the rule reaches the rule-maker's own private life, its logic loses, because love and self-interest were never inside the model. So such schemes survive only while the people enforcing them are exempt from them.
The state treats marriage as a lever for the population's future intelligence. It certifies each citizen's mental grade and uses taxes, penalties and permissions to steer who has children with whom. Private choice is recast as a public input, so affection becomes a regulated activity that needs a licence.
Read the future dystopia as the emergency bureaucracy of total war carried into peacetime. That bureaucracy includes propaganda films, compulsory schemes, officious departments and grading of citizens. Measures that were accepted as temporary necessities become permanent machinery aimed at citizens' minds and bodies.