It’s completely reasonable to want to know where someone’s finances are at!
That’s part of being an adult.
It’s also reasonable to expect your partner to manage their own debt.
Student loan debt, credit card debt, whatever.
There are sometimes good reasons for financial instability.
For example, I’ve been dealing with a chronic illness for years.
However, I wouldn’t expect my partner to manage my debt or handle my finances without negotiation and honest communication ahead of time.