This is the legend of King Arthur, a modest summary which is not exact appropriated as the story-tellers on google or movies. The story is same with descriptive changes. Here is adventure, tragedy and most of all a strong love.
I don't know if you heard the character Lionors in the legend of King Arthur she is the narrator of the book throughout. There is two or three pages of Arthur's POV which I don't remember. Lionor and Arthur are two star-crossed lovers ill fated to be together and there is Merlin who always guided Lionor and Arthur.
I will simply differentiate the variances between the myth of King Arthur in google/movies and Lionors.
Lionor is the uncrowned queen of King Arthur, she met him when she was only thirteen. She was the daughter of an Earl and he was a mere ward. Their courting was complicated because of their social class. But their romance blossomed and then Arthur was recognized as the King. Lionor cannot be any happier. They got engaged secretly but cannot bring this out in public as his reign is new.
Arthur here is a glorious, triumphant King who is loyal, honest and just, very different from his father King Urther who was brutal. And then for militant exploits and to secure the strength of his kingdom he marries Guinevere. Lionor is pregnant.
Merlin plays a guide to Lionor and Arthur. Lionor plays an active strength to Arthur. They barely see each other once a year. Guinevere's relationship with Arthur differs from the legend. Her attraction to Arthur's knight, Lancelot is mentioned but she was not involved romantically with Arthur. Arthur knows she sees Lancelot and she knows Arthur loves someone else. They both are kind to each other and gets along though they sleep with each other when they have needs.
Arthur fathers two children, a son with his sister (he was drugged for revenge) and a daughter with Lionor, both are bastards.
This romance needs a hero and Arthur defines here through Lionor. The input of this character classifies essential details of Arthur's adventure. His wisdom and compassion for his people stands out. Then there was his quest for the Holy Grail and finally his downfall in one last final battle with his son/nephew, Mordred.
Of Arthur and Lionor, their tragic and unrequited romance of doom was only broken by death. Sadly for Lionor who was created to be an additional strength to Arthur, loves and awaits for him until death where I imagine they meet at Avalon.