I imagine that Mist marriages were a mixture of political/cultural eugenics and Skyrim-esque brevity.
Like, a cultural "any decent person won't even consider someone for marriage until they're a chuunin. Those that do... Well, they almost always end up proving themselves to be the... disloyal sort, and are secreted away one night. And any Special Jonin/Jonin worth the rank won't even register another person as a romantic option until they're at least the same rank." That'd back up the discrimination that Hazou's mother faced, too. Wasn't he a clanless chuunin to her clan heiress jonin? Even if I'm wrong, and the discrimination was purely clan-oriented, it'd still be a cool idea.
Anyway, maybe there's an additional Mist notion of "for years/decades, we were held under the tyrannical thumb of a harsh jinchuuriki --who might as well be a fickle, angry god for all the difference it made. You didn't hear it from me, but most of us literally didn't know if we'd be alive next week, by the enemy's hand or by our own village's. Seriously, the fact that you don't have Bi-Weekly Loyalty Exams here is still kinda weird. So anyway, in Mist, courtship tends to be pretty quick and to the point. Why waste time you might not have, you know?"
Actually, now that I type this out, wouldn't courtship tend to be pretty quick in the ninja world --for Mist, especially? Short lifespans, deadly careers? I mean, ill-considered jokes about military spouses aside, there's valid reasoning to think that romance for ninjas in the EN is different than for civilians.
Maybe Yuno (someone from a highly isolationist, highly formal village where the average ninja's career isn't measured in the single digits) thinks that the brief, too-the-point courtships/marriages are irrational and maybe even a little foolish? It'd be likely that she thinks of such unions as "mere whirlwind romances that aren't likely to endure the entropic sands of time. I mean, they don't even know the given name of their partner's great-great grandmother! How can you expect the ancestors to give their blessing if you can't even honor them properly?!"
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Edit: minor wording and grammar alterations for clarity of thought.
Also, would Mari be okay with Naruto as Hokage? She's already served under the rule of one neigh-unbeatable jinchuuriki whose will couldn't be fought. Would she be okay serving under another one, even if it's one as (seemingly) benevolent as Naruto?
