Someone mentioned successfully reverse pickpocketing some frenzy poison into the husband inventory and he killed the spouse. With the CK you should check if the script for the reward is tied to the death of the NPC or some other condition has to be met.
Careful with this one: you also have to give the groom a pretty good weapon, or his first hit won't kill her and she'll flee off the balcony, where his second or third strike will kill her, but you won't get the reward because she's in the wrong place. There's also the danger of him getting distracted if he doesn't kill her fast enough, and go after ofther guys instead.
Also make sure you get rid of the guy who also stands up there, again for danger of distraction.