Zoro, despite being a stoic, generally quiet guy, is a great partner. He's always willing to listen even though he might not respond or be too invested, he's always a comforting physical presence when you need one, and in private he really is very, very loving. But he's human, and has human emotions.

You've maybe been a bit more needy today. Or maybe Zoro didn't sleep as well, or thousands of other possibilities. Whatever the cause, the effect is the same. You ask him one question or favor too many, and see an expression that is familiar but also unfamiliar to be directed at you. Anger. "Can you just leave me alone for give minutes? Do you need to be attached to my hip all day every day?" He snaps.