visiting: the two houses (Winthrop and Uppercross) are expressly described as being on very good terms. Perhaps Louisa believes she'll have a better chance succeeding in her scheme to reunite the star crossed lovers (and have the CW field alll to herself) if no one else has a chance to put their two cents in. I absolutely agree with the idea that Mary would prevent the visit if she knew about it. Since visiting your aunt is proper, and the families are on good terms, I'm left with the idea that Louisa is moving quickly in order to keep Henrietta moving with the momentum, and doesn't want to even pause for fear that Henrietta will have a chance for second thoughts.