Complex sentence: Bihter and Behlül's secret relationship continues for one year until the young man begins to fall in love with Nihal but with Bihter still on his mind.
Split into simpler sentences: Bihter and Behlül's secret relationship continues for one year, until the young man tries to fall in love with Nihal. He begins to fall in love with Nihal but Bihter is still on his mind.