Complex sentence: After winning a tourney, he had crowned Lyanna Stark Queen of Love and Beauty, passing over Elia; he and Lyanna later disappeared, which House Stark and Lyanna's betrothed Robert Baratheon saw as Lyanna's abduction.
Split into simpler sentences: After winning a tourney, he crowned Lyanna Stark Queen of Love and Beauty, passing over Elia. He and Lyanna later disappeared, which House Stark and Lyanna's betrothed Robert Baratheon saw as Lyanna's abduction.