Can you explain the relationship between the Soul and the body as described in Chapter 19? Why does this relationship lead to the cycle of Samsara?

Chapter 19 describes the relationship between the Soul (Atma) and the body as a supreme, unavoidable exception to the rule that friendship exists between those of similar nature. The Soul is changeless and imperishable, while the body is perishable. Despite their different natures, their affection is so extraordinary that they cannot bear to be without each other. As detailed in this chapter, it is this immense love and inability to remain separate that perpetuates the cycle of worldly existence, known as Samsara.