While it would work perfectly with in-game marriages, I would like this feature to work independently of that. What I had in mind was that you'd either get one half of the floor space each, where each player had control over the furniture layout of their side, or that they could decide to let both players furnish both sides as they pleased.

In case of a split, each player's furniture would just automatically be moved to their respective new single-person rooms.

With FF14 supporting real instances, unlike FF11, I also imagine that each player house could have something like an outdoors area attached to them, where you could do something like gardening or just chill out.

And again, it should of course be entirely optional so that anyone who wanted their own house for just themselves would not experience any penalties or downsides compared to a two-man house.