I think we are going to one day just see a return to the medieval European wedding. Basically used to be you didn't need a priest or an occasion... You just made your vows ideally in front of witnesses who could back you up that it actually happened.

Common advice to young women was not to get married in taverns because a raucous party where everyone got too drunk to remember what exactly was said and done could leave you with essentially a one night stand where everyone could just deny the groom actually made vows. This is the situation that eventually lead to marriages being registered by a church official and eventually making marriages an institution of the church.

Given how things are going with folks basically just telling the tax man when they are married under common law we are not super far off.