How to you get your spouse to undress

I think most of the other answers (or comments) here say pretty much the same thing I've read and heard here and in other places:

In Skyrim, marriage is forever.

That means there is no divorce, and death does not end a marriage either. You can never leave your spouse for another, or re-marry after being widowed.

That said, I believe the question here is a bit mis-phrased. By specifying "before I get married", I think the asker is actually looking for how to call off the wedding.

This can effectively be done by simply not showing up at the temple, at the appointed time. Then, go back to your betrothed and tell them you're no longer interested. After this point, you should be able to choose another partner.

Alternately, you can call off the marriage during the ceremony itself as well.

However, the previous statement still stands - once you've said your "I do"s, it's a done deal forever. (Or, until you reload to a previous save.)

If you're playing on PC, you can use the Console to reset the quest and remarry. Source

• Remove any Amulets of Mara from your inventory
• Enter the following into the console: setstage RelationshipMarriage 10
• Purchase an Amulet of Mara from Maramal, and complete the quest as usual—wear the amulet, find a spouse, agree to marry, and have a wedding.

Looking up "Lover's" on the in game console actually shows 2 magic effects called Lover's Comfort: CDA1F and 10D96C. This implies that while they share the same name, those two effects are considered different, so yes, they should stack with each other with no problems.

Even though there are two versions of the effect that can be seen in the console, the version that is applied from the spouse and the stone are the same (could be a bug), so currently they do not stack.