What is the main conflict in Idylls of the King by Alfred Tennyson, Baron Tennyson?

A popular theme among the Romantic writers, who greatly influenced Tennyson's
writing, was the conflict that arose between reason and emotion. It would be plausible to see the primary storyline of the "Idylls" as an allegory for this interaction. According to this reading, Arthur represents reason, often called the "ruling principle" in the human soul, a fitting title for a king. The role of reason—ideally—is to judge what the person ought to do and what he ought to avoid; in other words, like a king issues commands to his subjects, so reason issues commands to the body. When Arthur is newly king of his realm, he realizes that he wants a wife so that he will have someone to help him rule. Guinevere, then, represents the passions, which, if in proper accord, aid reason by making the person act with more force and purpose.