I would honestly be better for her financial future if she downsized and didn't act like an aristocrat. In that: If you go spending all of the money, eventually there won't be any money.
I dated a rich girl once, that was an interesting first experience for me since I was born in near welfare.
She didn't really seem to give a damn about money, but also because her parents sheltered her too much she didn't understand the gravity of the consequences of her actions, either.
As for who pays for what, I'm all for 50/50, but I'm also no chaser, either. Basically how I look at it is: If I'm already working 47 - 60 something hours a week or more, if that's not enough production to make ends meet than we need to downsize on expectations and living arrangements, or I'll be more inclined to go at it alone with my 47-60+ hour a week shifts. I work to live, I don't live to work. The idea of mutual respect, mutual independence, and mutual freedom is appealing to me. I just happened to have a good business comprehension because I've had to fight an uphill battle financially my whole life. Or in other words: The way you learn how not to be broke, is to be broke for a long enough time that you figure out how to get your **** together and at least stabilize it. I live within a budget, that budget is my paycheck, if that budget gets exceeded unexpectedly, that's why I keep a savings account to balance it out later, and if it gets exceeded because I slip up like a *******, than I just own that and ask myself what the **** I'm doing wrong and start reviewing my statement/transaction history to try to narrow it down to a science.
As for her extra money and assets? Just put it into savings. We'll call it the "Oh ****" money. As in, what to use when unexpected stupid things happen that throw you a curve ball. Example: "Oh ****, the car's transmission died" or "Oh ****, we've gotta go to the hospital" or "Oh ****, the pets need to go to the vet." That kinda thing.
Or for a more realistic example:
Currently, my car is a piece of ****. I didn't really buy it, I sort of got it through a relative after my car died but I owe the guy a small sum of money for it (pretty small for car, like CL ads kind of small). However, because it's over 20 years old, it breaks a lot of the time.
So, I had to open two savings accounts for it: One to put the money aside to pay it off, and the other to keep a small base of repair funds in so that it doesn't really effect my checking account, and I just try to live minimally in the between.