Manicheans regarded sexual relations as a defilement. The pure didn't have any sexual relations. Their beliefs were so bizarre they can only be considered as being absolute lunacy. Augustine, even though he was a Manichean, took a mistress who he latter dumped at the insistence of his saintly mother who arranged a marriage with someone more suitable. Since she was under age, he took up with another mistress. God only knows what happened to woman who had bore him a son when she was abandoned. How Christian of him. Evidently he didn't take much stock in Jesus' teaching that what God has joined no man can put asunder.
Augustine, along with Jerome, delivered the coup de grace to a reasonable sexual mentality. Their pernicious influence poisoned Christian theology for centuries until the Enlightenment began to challenge their nonsense. That the Catholic Church continues to be mired in ignorance only guarantees that it will increasingly be considered to be a ridiculous relic of ignorance and superstition.