How do you share expenses with your partner

My finance and I have lived together for about 5 years. My first 2 years out of college I paid living expenses as she was in graduate school. Then she made a bit less and we split rent and utilities in half, everything else there is no set breakdown . Now she makes about double as me and we still split rent equally. I mentioned I’d like to set budgeting standards for when we get married and put our money in 3 buckets out money, your and mine money. Money would be allocated to living expenses, savings, retirement, Individual discretionary money in same or similar percentages. She didn’t really like the sounds of that, she mentioned she liked what we are doing now but not opposed to having shared finances. What do you all think is the best approach that is financially responsible while allowing her to still have freedom to kinda buy most things she wants like expensive handbags and massages etc?