Complex sentence: Enranged by his family's disapproval of his romance with her, Hermann vows to never fall in love again and that once he legally can, he'll leave the Hunsrück all together.
Split into simpler sentences: Enranged by his family's disapproval of his romance with her, Hermann vows to never fall in love again. And that once he legally can, he will leave the Hunsrück all together.