Whether it's credit card spending or the secret cash stash, it's not healthy for a marriage to have secrets -- financial or otherwise. Broken trust and hurt feelings from financial secrets will put a wedge between a marriage. Often the damage is irreversible.
It's fine to have your head in the clouds when it comes to your soul mate. But when it comes to finances, it's important to have your mind on the numbers. That's because a financial mismatch between and your sweetie can sour any relationship fast.
Given the choice between the flailing middle class and obscene wealth...? I think I might actually take the first. Because I remember how it felt being married to someone who had a different approach to money and a completely different set of priorities. It was profoundly lonely.