Was there literally any mention of marriage in 1.0? Like, do we have anything to work on whatsoever?

Well, going on nothing, my idea would be something like...

'Traditional' marriage, lifelong monogamy between one male and one female, is probably an elezen invention inspired by the divine love between Menphina and Oschon. The symbol of Oschon, a walking stick, is probably involved; maybe the groom hands his staff to the priest, as if to say, "My journey is over because I've reached my destination." Hyur marriages would often be an imperfect copy of the elezen, though there's probably a whole other set of traditions from Ala Mhigo that are just as ancient.

Dunesfolk are nomads, they would have forager-type values. There would be no formal marriages and children would be raised by multi-generational families with grandparents and the like. Plainsfolk are farmers, so they'd need lots of kids, meaning everybody is expected to get married, probably at a very young age.

Roegadyn, it's hard to say. Sea wolves would not be happy to 'settle down' unless they thought they'd accomplished all they could in their lives, so marriage would be more like saying "Welp, I'm done, time to get old," not really something to celebrate. Hellsguard we know next to nothing about. It's probably something weird and ritualistic, like marriages last exactly 8 years and then you're not supposed to talk to them ever again.

Just my little ideas.