In the book "The Great Gatsby":

Why does daisy say she hoped her daughter would be a beautiful fool?

What kind of relationship do tom and Daisy have?

She was trying to imply that the life of a woman is a happier one in ignorance. If her daughter is a "fool" then she will never have to suffer the harsh realities of the real world. Think of the old saying " Ignorance is bliss". the less her daughter knows, the better. There relationship was merely one of convenience.