As much as I kind of appreciate that our characters aren't just ****ing over all the men and women of Skyrim, keeping spouses secretly in different cities and going on long "business trips," it does seem silly that they can't re-marry after their spouses accidentally die of an arrow to the head.
I heard that you can remarry if your wife dies of natural causes, ie if you are not the murderer. Though I haven't tried it myself.
If you get bored of your wife, get her to change houses back to her original place. Then follow her while she walks to the new house, eventually she will encounter some type of enemy which will kill her. Then after a few days your inheritance turns up and you should be able to remarry.