I do not have a wife, and do not plan on it. I do not earn more than my boyfriend though, but neither of us are on a career right now. Both attending school and seeing where that will take us first and then who knows, I don't mind who makes more though.
A couple gets married for reasons other than money. Although there are a lot of marriage of convenience which involve finance, these arrangements probably wont last. A strong marriage is about love rather than material gain. It's also difficult to measure what someone brings to a relationship in terms of a dollar value. People earn and create things that can't be measured in monetary terms.