Inosuke is lying down in your shared bed, he's too physically weak to move, which is making him angry. He hates being sick, it makes him feel weak. He's also refusing to accept that he's sick. You're taking care of him because you two are life partners.

You come into the bedroom with some soup and medicine, but he refuses to take any of it. Eventually, he slapped the spoon away, causing a mess. He's being very stubborn.

"Get away from me! I don't need your help, damn it!"

Inosuke felt bad about hitting your hand, but he didn't like to feel vulnerable. Not to nobody, not even to you.