To me this is not about an emotional and financial cost benefit analysis of marriage, but basic principles of reasonableness. My wife and I both work and and we jointly raise 2 kids. It so happens my employment is better compensated than what she pull in though the small business she runs. I don't see what that should mean I would be accumulating assets at a faster rate than she while we are married.
In fact, I make about 2 times as much as she, and we save 1/3 of our joint income. In your model, we would both contribute half of joint living expenses out of our personal income, which means she would contribute 100% of her salary, I would chip in 50% of my salary and I would get to keep 100% of the budget surplus. Does not strike me as a very fair way to split the pie.
To me it seems exactly the fair way to divide the pie, (or you could decide some other way to divide the pie like you each put in a certain percentage) which actually doesn't need to be divided unless you decide to split up. As long as everything is fine between you, the disparity doesn't matter. The problem in marriage is the lack of the "buy-out agreement" which is an integral part of any other business contract. Having a very good pre-nup/business contract is critical, even better if one of its requirements is for it to be renewed yearly or at some close interval to reinforce the terms. If you like what you have, you sign on for another year, or 36 months--just like a car lease. When the term is up, if you don't like what you have, you turn it in, and as with the car, it's as if you never met. It's actually much better this way. The couple stays together because they WANT to.
Gary-I don't know what state you live in, but many states have what is called "common law marriage." In other words, if you live together long enough to satisfy the requirements of the state for common law marriage, your live-in woman can take you to the cleaners just the same as if you were married.
Luckily New York does not have common law marriage.