Investing Student Loans??

My girlfriend and I have been together for two years, and she’s currently in a doctoral program. I pay for all the bills and she lives with me for free while she’s in school. If she takes out student loans (the interest rate for a federal loan, which we were looking into is 8.07%) to cover her “living expenses” and gives me money for her “share” of the rent, groceries, gas, and other bills, would it be worth it for me to invest that money on her behalf in an ETF like VT or VOO until it’s needed?