Complex sentence: In Hindu culture, for the most part, a marriage alliance between cousins is looked down upon though there is the case of Arjuna marrying his first cousin Subhadra, the sister of Krishna.
Split into simpler sentences: In Hindu culture, for the most part, a marriage alliance between cousins is looked down upon. However, there is the case of Arjuna marrying his first cousin Subhadra, the sister of Krishna.