What is Framton nuttel's sister afraid will happen if she send him out to the country?

Framton Nuttel's sister is concerned that if she sends him out to the country, he might encounter situations that could exacerbate his nervous condition. She fears that the solitude and unfamiliar environment may trigger his anxiety or lead to further health complications. Additionally, she worries that he may not be able to handle the social interactions or the local customs, which could overwhelm him.