Is it a Torah concept that children can not leave the house and have their own place before getting married? We are dealing with Noahides here.

For Noahides, the situation is different from what applies to Jews. According to the Torah, there is no formal concept of marriage for Noahides in the way that exists for Jews. When Noahides are together, they are considered married, and when they separate, they are no longer married. There is no mitzvah of getting married for Noahides, and no formal marriage ceremony is required. Regarding children leaving the house before marriage, the Torah perspective for Jews is that ideally, a man or woman should not leave their parents' house until they are married. For a woman who is still in her father's house and unmarried, her father is responsible for her. For a man, it's problematic for him to live by himself because it can lead to more opportunities for sin. However, this is the halacha for Jews, not necessarily binding on Noahides in the same way. For Noahides, the challenge is that there is no organized structure or community framework like there is in Judaism. When you raise children as Noahides, they may grow up and want to date or marry someone who is not a Noahide or is even an idol worshiper. You can tell them they shouldn't marry a Christian because they're a Noahide, but without the framework of Torah law binding on them as it is on Jews, this becomes very difficult to enforce or maintain over generations. Being a righteous Noahide is actually much more difficult than people think, precisely because of these issues. There is less structure, less community support, and the difficulties can be greater than those faced by Jews who have a clear halachic framework and community structure to support them.