Complex sentence: After her death Denethor became sombre, cold, and detached from his family, but the relationship between Faramir and Boromir, who was five years elder, only grew closer.
Split into simpler sentences: After her death, his father, Denethor, became sombre, cold, and detached from his family. However, the relationship between Faramir and Boromir, who was five years Faramir's elder, only grew closer.