I have recently twice had the experience of commencing a modern retelling of the King Arthur legends with enjoyment, only to abandon the story before the end due to a kind of revulsion at the gross psychological implausibility of the narrative turn.
The problem in both instances was that well-established characters, characters I had got-to-know, suddenly began behaving unnaturally, unbelievably, by tortured-logic - due to their actions being artificially shoe-horned into a pre-exiting plot shape.
The fault, in both cases, was that the authors had tried to stick to the shape of Thomas Malory's Morte d'Arthur (middle 1400s) - which (for all its excellences) is merely a compendium of diverse and originally separate legends, cobbled-together into a semi-coherent set of loosely-linked stories.
As indeed is the Arthurian story itself - apparently consisting of two separate strands of ancient legend - one about the prophet and wizard Merlin, and the other about a noble war leader and exemplary character called Arthur - probably based on real people, probably from different times and places of post-Roman Britain (from the 400s AD onwards).
These strands were brought together mainly by the genius of Geoffrey of Monmouth in the middle 1100s to make the basis of the Arthurian story. And these are the Arthurian elements which I love - especially those concerned with Merlin.
These are the British elements of the King Arthur story - the true 'Matter of Britain'.
The later additional French stuff about knights, chivalry, round tables, courtly love, the Lancelot/ Guinevere adultery, and the Grail Quest I find more-or-less repellent - although I can tolerate them if they are subordinated within the narrative.
(I find the Grail Quest a particularly horrible intrusion. It's hard to put my finger on why; but for me it gathers and concentrates many of the very worst aspects of medieval Christianity - exactly the kind of corruption and pathology masquerading as health and purity that helped keep me away from Christianity for so many decades.)
Of these later elements, that of courtly love is, for me, the worst. The business of knights 'serving' their ladies, wearing their favours, the stupid stuff about 'honour', courtesy and being held bound by a casual and unconsidered word to do some ridiculous or wicked thing...
Bah! it is Frenchified, decadent and anti-Christian (as made clear by the romance Sir Gawain and the Green Knight from the late 1300s; in which these elements are a threat to the goodness and purity of Gawain, and his stubborn adherence to this courtly code is revealed as absurd and unworthy).
Consequently, from my perspective, all version of the Arthurian legends I have encountered (in movies, TV, novels and poems) are extremely imperfect and unsatisfactory works of art - through which something strong and important may shine.
In this my attitude seems to resemble that of JRR Tolkien - who, for all that he tried his hand at an extended Arthurian poem, had strong reservations about the thing as a whole, even as he responded powerfully to specific elements.
In sum, I wish that some more authors could put Malory behind them, and re-imagine the Merlin-Arthur aspects without the effete continental intrusions - to create a noble and psychologically plausible tale that taps into deep roots of British myth and the Christian impulse.