Complex sentence: This humiliated Warwick, who had negotiated an agreement with Louis XI of France for Edward to marry the French king's sister-in-law, and relations were further aggravated by the subsequent influence of the Woodvilles, who successfully opposed Warwick over foreign policy.
Split into simpler sentences: This humiliated Warwick, who had negotiated an agreement with Louis XI of France for Edward to marry the French king's sister-in-law. Relations were further aggravated by the subsequent influence of the Woodvilles, who successfully opposed Warwick over foreign policy.