to laugh at, to pity, afflicted, sad
悝 centers on a troubled emotional state that can swing between outward mockery and inward sorrow: laughing at someone, pitying them, or feeling afflicted and sad. The meanings share a core of emotional disturbance directed at oneself or others.
悝 combines the heart radical 忄 with 里, which likely contributes the sound. The exact historical development of the meaning is uncertain.
The heart radical 忄 next to 里 (village) suggests a heart troubled by village gossip: one moment you laugh at someone, the next you pity them, and soon you feel afflicted and sad.
For カイ, imagine a sad clown named Kai who laughs at others but secretly feels afflicted: Kai -> カイ, and his heart 忄 is full of mixed emotions.