Aside from the fact that the older brother may have confused Yurito and his older brother, I think he may also not know everything about his mother's story. I get a feeling that his mother may have originally been with Coro's father, but either through magic manipulation or some sort of threat, their mother got with the older brother's father. After they had the older brother, his father may have realized that his mistress would not actually love him or maybe their deal was over, allowing their mother to go back to his actual lover. It's speculation but I just think that because the village admired the older brother's father, they either didn't realize the truth (just like how they are now not suspecting anything being wrong) or they are trying to "protect" the older brother from the truth due to their biases. My thesis is just that the village sucks and is biased and I would hate living around them. Just theorizing and stuff lolol
Aside from the fact that the older brother may have confused Yurito and his older brother, I think he may also not know everything about his mother's story. I get a feeling that his mother may have originally been with Coro's father, but either through magic manipulation or some sort of threat, their mother got with the older brother's father. After they had the older brother, his father may have realized that his mistress would not actually love him or maybe their deal was over, allowing their mother to go back to his actual lover. It's speculation but I just think that because the village admired the older brother's father, they either didn't realize the truth (just like how they are now not suspecting anything being wrong) or they are trying to "protect" the older brother from the truth due to their biases. My thesis is just that the village sucks and is biased and I would hate living around them. Just theorizing and stuff lolol