Complex sentence: In 1458, she married her first husband, William Bonville, 6th Baron of Harington, who was, like her own family, a strong adherent of the House of York.
Split into simpler sentences: In 1458, she married her first husband, William Bonville, 6th Baron of Harington. The Bonvilles were, like her own family, staunch adherents of the House of York.