The blind date man is afraid that the woman will live in her grandmother's house, mainly because this way of living may bring some psychological burden and discomfort to the man. The following are possible reasons:

1. Traditional concept: In the traditional culture of China, family is an important value, especially the relationship between parents and children. If the woman lives in her grandmother's house, the man may feel that the woman lacks a sense of identity or responsibility for the family, which may affect their future relationship.

2. Social pressure: In China culture, family relations and social relations are closely related. If the woman lives in her grandmother's house, the man may feel excluded or not recognized, which may bring unnecessary pressure and contradictions to the relationship between the two.

3. Private space: In China's traditional concept, both men and women need a certain degree of private space and independence. If the woman lives in her grandmother's house, the man may feel that his private space has been violated or restricted, which may affect the development of their relationship.

Of course, the above are just some possible reasons, and the specific situation needs to be analyzed according to personal cultural background, values and living habits.