I have often heard about the possibility that the player should have to be unfaithful.
However, I haven't heard as much on the possibility that the player could be cheated on as well. How should the player learn about his/her spouse's unfaithfulness? Should he learn that by hearing rumors (though this wouls be weird seeing NPCs talking openly of the spouse's behaviour in front of the player) or spy him/her? And once he knows, what should be the options the game offer him to react?
This presents fascinating opportunities for some really fun quests, and a much more interesting relationship with that NPC; however, sadly I think it would be too ambitious for the devs to pull off in the vanilla game. Fortunately, I imagine there are a lot of these kinds of features that could be added to a relationships overhaul mod, enhancing the complexity of romance, marriage, cheating, divorce.
In a similar context, will friends and spouses be able to lie and manipulate the player, leading her/him commit crimes he otherwise wouldn't so that they can reach their own, possibly evil, hidden purposes? How should then the player learn their true goals?
I certainly hope so!
Will the spouse be able to use every item that happen to be at his or her disposal in the house shared with the player? Or even which is not in that house but in another house belonging to the player?
I think it's likely that spouses will consume food items, as we have seen NPCs consume items in previous Bethesda games.
I'm not so sure about spouses being able to relocate to various houses in cities spread out across Skyrim. I suspect spouses will only move in with the player if the PC buys a house in their hometown. The reason is because if you marry a baker, for example, or a merchant, s/he is not going to trek from Windhelm to Solitude every morning just to open up their shop. Since spouses will likely still have some sort of daily activity routine and jobs similar to whatever they did before marriage, I don't believe they would be able to relocate to far away towns unless there are a few select NPCs without jobs, that are designed to be able to relocate and serve primarily as adventuring companions.
Will it happen that the spouse becomes jealous and suspicious while you did not cheated on him or her? In that case, will you be able to find and, err, dispose of the source of the rumors you could suffer from (possibly a dismissed suitor who wants to seduce your wife, or even to seduce yourself once the wedding is broken)?
Fascinating idea - if this is not in the vanilla game it would be great to incorporate into a Relationships Overhaul Mod.