Complex sentence: Faustina's father had ended the engagement between his daughter and Verus, and now arranged for Faustina to be engaged to her maternal cousin, Marcus Aurelius and Aurelius was adopted by her father.
Split into simpler sentences: Faustina's father had ended the engagement between his daughter and Verus. Her father had arranged for Faustina to be engaged to her maternal cousin Marcus Aurelius and Aurelius was adopted by her father.