I have always gotten the impression that there’s a large gap between society and Society in this game. Society, the Faction with whom one can get renown, is the rarified exalted (or so they believe of themselves), and more-or-less the aristocracy and their hangers-on. Capital-S Society is very stodgy and conservative and also very concerned about the form and appearance of things. As a result, anything that you do that intersects Society requires that one Put On Appearances and be very Proper. All-in-all, this group of people pretends that nothing happened to London except the lights got a little dimmer and the wines a little more mushroomy.
Meanwhile, lowercase-s society, the gestalt whole of Fallen London consisting mostly of people trying to get through their lives, has changed. And they acknowledge those changes. And Society judges them for that, and uses that as a pretext for excluding them for Society (but of course they never were going to include them anyways). Capital-S Society believes itself to be the bastion against the advancing wave of decadence and decay that is the rest of London changing and adapting and advancing and evolving. And Society members have a centuries-long tradition of finding excuses why anyone else is inferior to themselves, as a part of a reflexive talent for acquiring and keeping power.
What this means is, there’s a very large gap between what’s more-or-less accepted, and what’s "acceptable." People in this game boink in dark corners at the drop of a hat, but exposed ankles are still considered scandalous. Why? Because everybody does it, but everyone pretends that no one does it. On the streets, in the bars, on the Docks, everyone looks the other way or carries on with a wink and a nod. But in the fancy salons or at church, everyone still faints at the merest suggestion.
(I am led to believe this was true to an extent in historical Victorian London itself. Appearances to the contrary, there was still an adequate amount of gambling and whoring and premarital smooching that went unacknowledged, especially by the upper class. But I’m not a historian.)
Fallen London is very much a game about secrets, and about the complexity and contradictions of human behavior, and about people pretending to be things that they’re not. I think it’s very much in-setting to do things, and accept things, but still pretend (when required) that such things are not done, or not accepted.
Marriage is, by necessity, one of the old-school traditions or institutions or whatever you call it. Especially a big fancy-ass wedding held at the Bazaar with Masters and Bishops in attendance is very much one of the Captial-S Society things. As such, one Maintains Appearances for the purposes of actual, legal, ritualized, formal matrimony. What one does in one’s own lodgings with or without one’s spouse is not the business of anybody except yourself, your spouse, any number of mutually consenting parties, the coalman, the urchins on the roof, and whoever the urchins are willing to sell the information to for a half-cooked rat. And if you’ve any sense, you pay the Urchins yourself.