They are a human country and supposedly hunted the demihumans who know of it, that is probably why? idk. On another note... no BL please. I would rather have loli love than this route.
This series would be so much better if the mc actually used his magic to train himself beyond any limit, and if it were a actual seinen series with not a inner bitch mc who will stay virgin till the very few last chapters (Most likely) even when there are plenty women showing interest in him...