Complex sentence: When Franck left him just before his 21st birthday, he was despondent; he returned home, though his family relationships were also strained; his father remained convinced that Wolf was a ne'er-do-well.
Split into simpler sentences: When Franck left him just before his 21st birthday, he was despondent. He returned home, although his family relationships were also strained; his father was still convinced his son was a ne'er-do-well.