I think kinship ties should be and should have always been available to declare or establish at the state level, and calling it a marriage just confuses the issue. I also don't think it should be restricted to couples, either, but it is.
I think the churches should have their business and the state should have its own business. Modern marriage really only serves to invite the state into the bedroom, so I don't even think about it as something that should be fought for. I mean, have at it if you want it, but I think you'll find that it just invites more problems than it solves. I don't recommend anyone ever get married in 2023.