They're companions. Animals have feelings just like we do. When you hurt an animal like you hurt a human, it feels the same thing! You probably never actually took care of a pet to witness this! [Ugh. Jade will be patient though. Maybe she can reason why Saionji should treat her Pokemon better.] They have shorter lives and they can get hurt, and if you don't take care of them, they don't get better.

It won't kill you if you take care of yourself.