Complex sentence: There is no doubt that the refusal of the prince was due to her behaviour towards him, as she was favouring her son-in-law, Shahryar, at the expense of Khurram.
Split into simpler sentences: There is no doubt that the refusal of the prince was due to her behaviour towards him. She was favouring her son-in-law, Shahryar, at the expense of Khurram.