I 23m and 22f want 50/50 split?

For context, my wife and I agreed before marriage that we would split all expenses 50/50 regardless of who earned more. At the time, we both agreed to that arrangement.

Now that I’ve graduated and gotten a high paying job, I make approximately $123k more than she does, and she wants me to cover 80% of expenses while she pays 20%. I refused because that goes against the agreement we made before marriage. She argues that splitting based on percentages is more fair now. If were to do that it would me around 75% while she 25%z

She also brings up the fact that I will likely inherit a significant amount of money from my parents in the future, while she does not have the same kind of financial windfall. Because of that, she says I benefit much more from the 50/50 arrangement than she does.

The frustrating part is that she is not financially struggling. She mainly wants more disposable “fun money.” I honestly do not know what to do anymore.