Dreams are the subconscious that we cannot see during our waking hours. Dreams are a reflection of what is going on in real life. Perhaps you are going through a trying time. Your dream doesn't mean you want your spouse dead, but maybe you have some underlying anger that has not been addressed.
There are many different approaches to dream interpretation- it's not an exact science. However, the most common interpretation suggests that this signifies there is some conflict in your relationship at the moment. Don't worry, it DOES NOT mean that you really want to hurt them. It could be your subconscious expressing feelings of frustration towards them or just towards your life in general. Or, you could be one of the people whose dreams have little or no meaning at all, in which case it is just a random figment of the imagination. I wouldn't be worried.
You might be mad at them or hurt by something they did inside...or maybe something triggered it during the day.
I just hope that you don't decide to follow your dreams, in this case.