She knew that in the cottage she'd left Harry and Ron, and most definitely Ron, were furious and fuming at her, but this, Hermione knew, was how it had to be done. It was the same as the day she had gone to obliviate her parents, erase herself from their memories - she didn't ask permission, she didn't even tell them what she was planning, because even though it was dangerous she knew that it had to happen. Ginny had to know, at least the things they had agreed she should know, and telling her was a bit they hadn't talked about. Owls weren't safe, though, and they couldn't be sure the journals were, so one of them had to go. And Hermione was the most expendable, now that they knew what the last of the hocrux were, she knew that even if the boys would never admit it.
She wasn't out to get herself caught, though. She used the last of their last batch of polyjuice and became Fleur, at least for long enough to get her to the WWW, and she used the wand Bill had brought her, because it couldn't be traced to her and because she had precious few other options. All in all, with the way that the twins had set up their wards on the shop, she was able to get in easily, and by the time the polyjuice was wearing off, she was in the basement, waiting for Ginny to come through the tunnel entrance.