What kind of women are in your life, people? This is crazy!
OP - Don't tell your girlfriend how much you make. You're not serious enough about her if you're asking that here.
As a woman, I understand the sentiments that are in this thread. I get what y'all are saying about protecting the little wife at home from too much knowledge of the big, bad world. In theory, it's a great sentiment.
My father has done this for my mother for more than 40 years of married life. He's spent the last ten years or so setting up trusts and laying out complex plans to avoid estate taxes and such. Unfortunately, my mother who was always protected from having to understand how the money worked hasn't a clue how to handle her husband's will or even what the basic terms of his estate mean. She's very smart, but she's been told her whole life not to worry about it, so she hasn't. If you think my father is going to leave it up to non-family members (lawyers and accountants) to tell my mother how much she has to live on for the next 30 years, you're so very wrong.
He's been driving her crazy with lists and instructions because he's convinced that she'll outlive him by at least 20 years, possibly even more. (Her mother is currently 91 and going strong.) She's doing her best to understand, but it's a steep learning curve for someone who's been pampered and patted on the head for decades.
I can't tell you how to run your marriage, and I'm guessing that the level of respect for your wife, her intelligence and her intentions toward you are wrapped up in your decisions about income disclosure. If you have an honest relationship, your wife shouldn't have any problems with structuring your business so that the company is protecting the bulk of the money. In fact, she should prefer it since that same company is protecting her income and her way of life from any major fuck-ups you make that lead to lawsuits.
At the very least doesn't your wife get some sort of clue when she signs the joint tax return? Or maybe you just don't trouble her with that sort of financial detail either since she'd be signing off on something that could be legally binding for her, but totally safe since you've already handled all those pesky details for her. (And before you say it, I realize the tax return looks nothing like real income thanks to separate business filings and write-offs/deductibles. However, there is a line or two in there that would give her a nice idea of what's coming through the door if she cared to look.)
Best of luck, gentlemen.