Pain, sorrow and misery trigger a chain of hate or aversion.

Verse 2.7

सुखानुशयी रागः ॥७॥

sukha-anuśayī rāgaḥ ॥7॥

Attachment is that which dwells upon pleasure.

Verse 2.8

दुःखानुशयी द्वेषः ॥८॥

duḥkha-anuśayī dveṣaḥ ॥8॥

Aversion is that which dwells on pain.

Dwelling on pleasurable experiences ignites desire and a sense of attraction,

which creates attachment. Pleasurable experiences generate greed and lust,

which strengthen attachment and stimulate a greater craving, as one always wants more and more. 

One becomes absorbed by the pursuit of pleasure, and addicted to gratification of the senses. The aspirant may thus forget his chosen path and allow himself to be caught up in sorrow and sickness.

Pain, sorrow and misery trigger a chain of hate or aversion. Recollecting lost pleasures, tormented by desires unfulfilled, man is led to sorrow. 

In extreme distress he comes to hate himself, his family, neighbours and surroundings, and feels a sense of worthlessness.

A discriminating person strives to acquire knowledge so that he may strike a balance between sukha and dukha and live at the mercy of neither

pleasure nor pain.

PATANJALI YOGA SUTRAS