We come from the modern era where marriage requires legal documents and witnesses. But Traditional Chinese and other cultures don't require that, and its mostly ceremonies with the witness of elders and paying respect to elders and Heaven.
So when a couple in wuxia take oath with the moon or sun whatever, does that make their marriage legal or legit? Do they need a third party as their witness?
So what makes marriage in wuxia legit? I mean for some characters they don't have parents or in some circumstances no witness of their oath to each other to become spouses, so I'm just curious.