The Rumors are Incorrect!
The Wang Clan has a tradition that has lasted from the times where they weren't even part of the Big Four. Every single girl and boy who is born into the clan is given a seal called Wang's Mark. That mark itself doesn't have any power, can't help with cultivation, nor be sold since it only has value for the Wang Clan.
Once a woman or man is going to marry, they give their mark to the one they love. Once it is done, it is determined that they will stay together until the day of their deaths. But that only happens after the marriage is concluded. Before that, the mark only represents the girl's or boy's intention of marriage and can be retrieved before it happens. One case would be the partner's betrayal or death, for example.