Why does the soul experience pain if the soul itself is indestructible and spiritual?

The soul, being eternal and spiritual as confirmed in Bhagavad-gītā 2.20 ("For the soul there is neither birth nor death at any time... He is not slain when the body is slain"), cannot itself experience pain, for pain belongs to the material covering. As stated in BG 15.7, the living entities are "My eternal fragmental parts" who, due to conditioned life, struggle with the senses including the mind, meaning the pain is experienced through the mind-body complex rather than the soul's essence. The soul merely witnesses the suffering of the material organism, much like a person watching a dream, untouched by the dream's pains. According to BG 13.22, the living entity meets with good and evil "among various species" due to association with the three modes of material nature, which create the illusion of ownership and identification with the temporary body. This conditioned consciousness—thinking "I am this body"—is the root cause of all pain, for when the soul forgets its spiritual identity, it becomes subjected to the anxieties of material existence. The practical guidance is to revive our eternal relationship with the Supreme through devotional service, thereby freeing ourselves from the miseries of the material world and realizing that we are, in truth, the indestructible witnesses beyond joy and sorrow.