Love and marriage, as the Frank Sinatra song tells us, go together like a horse and carriage, and while I by no means desire to disparage the institute, that might be a problem when it comes to writing speculative fiction. I had the thought as I was recently rereading the Mistborn books which, minor spoiler warning, include a marriage, and since then I have been turning the matter over in my head, considering it and polishing it up into this post.
The problem isn’t with marriage per se, but rather with its cultural underpinnings and significances. Like, for instance, someone from a mid-latitude region assuming that everywhere has four seasons, marriage is such a fundamental part of our societal context that it can be difficult to even be fully aware of the assumptions that therefrom arise. In other words, marriage risks being anachronistic in certain works of speculative fiction, especially alternative world pieces.
I do not think that it stretches the imagination that something akin to marriage would arise in many human civilizations, even those that do not share a history with our own. There is significant evidence to suggest that monogamy provides numerous benefits as a society advances beyond the hunter-gatherer stage, and not just in civilizations that practice primogeniture. Furthermore, formal ceremonies and celebrations of various forms of matrimony characterize diverse human civilizations throughout both spatial and temporal regions, so supposing that there might be an official enactment of a marriage-type pact is not outlandish. Designing an institution of marriage for your world-building will necessarily echo those with which we are already familiar, which is not wherein the problem lies.
Rather, what makes marriage in speculative fiction jarring is the way that the characters interact with the institution. Even if we can prevent an in-world marriage ceremony from feeling anachronistic with respect to real-world ceremonies, if the characters approach it with the same attitudes as modern persons bring to such events, it will tend to throw readers out of the immersive experience that we as authors try to build with our stories. Simply by virtue of the differing relative time period and societal context, marriage should be perceived and approached differently in most fantasy worlds than it is in the “real” world.
That time period piece is worthy of greater attention, and starts to delve into one of those “author’s choice” matters where the writer must decide where they want to fall on a continuum. The more faithfully you can build your character to their spatial and temporal contexts, the more believable and immersive your story will be…up to a point. At some point, you will end up with a character to whom your readers will be unable to relate in any meaningful way. Sanderson (I know, I’m referencing Sanderson on writing again) has suggested that all good characters are, by necessity, anachronistic in their own contexts, consisting to varying degrees of transplants from our modern world into different contexts, not in the overt sense, like in A Connecticut Yankee in King Arthur’s Court, but in a literary sense.
Maybe it’s impossible to fully evoke a different time period or a different context, with a completely different history, in a way that is perfectly faithful, if we have never experienced it for ourselves, just like it may be impossible to write a truly alien character. I would argue, though, that we can at least approach writing from an immersed perspective, rather than an anachronistic one. Conn Iggulden’s The Abbott’s Tale is a good example of this. Furthermore, reading period pieces like the Babur Nama or even Plato’s Dialogues can give us a better idea of how to craft and characterize characters that are true to their own contexts, not to ours.
Returning to the idea of marriage in speculative fiction, there are two keys I’ve identified to making this convincing. One: don’t only mention marriage when you have viewpoint characters getting ready to get married. It should be something that is sprinkled throughout the world and well-established as a significant cultural event (or insignificant, I suppose, if that’s how you want to spin marriage in your world-building). Two: do some research about different marital practices in the real world both today and throughout history, with a special focus on how those practices arose and from where they derive their various significances. Christian marriage practices, for instance, have a lot to do with the European practice of primogeniture and the Church’s role in Western Europe after the Roman Empire receded.
As far as general advice, though, the best that I can give is that you should treat marriage in your stories like you do any other world-building element, and not base it on unquestioned assumptions that you’ve made based on your own lived experience. Being aware of its implications and bases, and the context in which it is perceived in-world, you will be more effective at crafting an immersive institution of marriage for your world-building and for your characters, which will ultimately be of more meaning and significance to your readers than a ceremony with which they might be familiar but which does not necessarily fit into the world you have crafted. And that, I think, is as close as I’m ever going to come to giving marriage advice on this site.