It is said that ancient people had to marry first and then concubines?

Not necessarily, there are concubines first. If you have a lover first, but the other person is not the right person, then you have a concubine first.

It's clear here that I can't get married, I can only say concubinage. According to the traditional marriage custom, concubinage is not allowed to visit the bride, and there is no need for matchmaker's words and parents' orders.