She may have been right about that, but she was pushing it now, considering he'd just returned from having left angry. And he wanted time to himself now, since she was still there and he still wasn't completely over being upset, especially since she still didn't seem to understand where he was coming from.
"We, or rather I... need stuff to eat this weekend. So I'm going shopping. I won't be gone long," he said, so that she knew he wasn't going out to the Leaky or something like that. But he needed to clear his head.