That's what I did with her too. I can't tell you how tired I was of going into my house in Whiterun, and seeing some stranger in there. I'm like, "I thought you were going to guard my belongings with your life." Now its just me and Ysolda, my wife. I tried to get her to follow me to Boethia's pillar, but she didn't have the dialog option. Apparently, Betheda doesn't condone sacrifing your spouse to a Deadric Prince. Which I thought would be a much more appropriate victim for Boethia. After all, you trusts you more than your wife?