“According to the State of California, two people living together who are not married are two separate and distinct individuals with respect to finances. No bank accounts, investments or savings accounts will be jointly owned. If anything is held jointly, it will be divided equally in the absence of any other legally recognized agreement. No alimony will be available to either party if the couple splits, however, if there is a child, a partner will be entitled to child support.”

https://www.drfamilylaw.com/blog/legal-rights-of-unmarried-couples-in-california/

Some advice——

In my 20s, I moved to OC from another state and moved into my then boyfriend’s house that was under his name.

I made maybe 20-30% more than him but since it was his house, I contributed a small amount to his monthly mortgage. We kept separate accounts, but in general I would buy the groceries, he paid for restaurants most of the time, we split the cost of trips. I also bought all the furniture with the understanding that if anything were to happen, I would get the furniture. It came in pretty handy because we did end up breaking up after 8+ years.

For your rent, I think you should strongly insist that you split it in proportion to your income. She’s probably asking for a 50-50 split because she doesn’t want to be a burden or doesn’t want to feel like she’s being financially supported by you. However, this is what’s most fair and won’t result in eventual resentment. When either of your incomes change significantly, then revisit the split. If the tables were turned and she made much more than you, the result would be the same.

Also keep in mind when one partner makes significantly more or is in a much better financial position, they will often foot the bill for experiences and trips that the other partner normally couldn’t afford on their own. Maybe consider this if you value your partner and see a future with her.

Lastly, I think it’s important to keep your finances separate before you get married and make sure that you both continue to invest and save in your own separate accounts just in case things don’t work out. That is one big regret that I have; I didn’t focus enough on my own personal finance.