"BLOODY HELL, HERMIONE! It's MY wand!" he shouted. "You had no right to take it from me to begin with! Now tell me where it is!"
Right in that moment, Ron had no qualms about yelling. He'd let his anger sit all day, building up while he tried to ignore it. And yes, he was angry at her. But she was getting far more than that and he needed to get out of there. He still didn't know quite why, but he did. And she certainly wasn't helping the situation.
"I mean it," he said, only slightly calmer. "Tell me where it is."