His honour rooted in dishonour stood,
And faith unfaithful kept him falsely true
A magnificent piece of writing craft, but that isn’t the point. The point is that such is life for imperfect creatures mired in a systematically imperfect existence, replete with ironies, contradictions, and the consequences of ethical failure. I know the situation, vaguely. I know what it is to have the occasional flushes of success and pride in honourable achievements ever borne ignobly away on the black tide of guilt.
The pure Elaine dies of a broken heart. The impure knight lives on in sorrow. The adulterous Guinevere seeks Lancelot’s forgiveness for her jealousy. Reality survives.
(The closest I ever came to the purity of Romantic love was ended with the words ‘There is nothing to be done.’ They weren’t mine on that occasion, but they were inevitable.)