I have many friends who marry their uni classmates (i.e. husband and wife same university degree work in roughly the same line) also end up wife earned more. Shows that in the working world, sometimes luck involved, wife may had more opportunities for promotion etc - especially in banking/finance where there is really high variance in salaries.
From the financial perspective, the best kind of wife is one that earns more than she spends. Absolute income is not critical. If your wife earn $10k but still takes your money to spend, you will be worse off than a wife that earns $7k but is able to spend and save from her own income.
Income > expenses. Where I have I see that equation before?
And unless you are totally blinded by emotion, you should be able to get some idea before marriage whether your future wife/spouse is going to be a financially high maintenance spouse or not.