A cop who is accused of assaulting his wife should be fired - if it is proven that he did it. It would be grossly unfair if he got sacked then it turned out it was all made up. If he is caught doing it then he should definitely be fired and arrested and then prosecuted. He is supposed to be abiding by the law that he dictates.
Assault, especially domestic abuse is behavior that is unbecoming of an officer. Not only that, but it is evidence that he might use poor judgement when deciding how much force to use or whether or not to use a weapon when dealing with a suspect. At the very least he should be suspended until the trial is over.
In cases of domestic violence, the benefit of the doubt should always be given to the victim, no matter what their spouse does for a living. That said, a police officer should not be fired because of the accusation, barring clear and convincing evidence. Lacking that, they should be suspended until they either plea guilty or are found guilty.
A cop who is accused of assaulting his wife should not be fired. In fact, anyone ACCUSED of doing something bad should not be fired at all. Last time I checked we are a nation of laws that assumes a person is innocent until proven guilty. Is that asking too much before taking a person's livelihood away from them?