A married couple should enjoy comparable standards of living regardless of who makes more money. Other than that, you do you.
My husband and I are both divorced. We don't have a prenup. My thinking is, either you married an asshole or you didn't. If you married an asshole, a prenup won't save you, and if you didn't, you don't really need one, but YMMV. The process of talking through what would happen may be just as valuable as the legal agreement. In our case, we were able to see how the other person had handled their divorce and that we are fair people. We have an approximate idea of how much we each came into the marriage with and a handshake agreement that if it goes south, we leave with that plus half of what we made together.
(In fact, I think my husband was maybe a bit more generous to his ex than was strictly necessary, but better that than the reverse.)
It's true that you either married an asshole or you didn't. But a lot of people don't find that out until they've been together for years. Some people say 'I knew in my gut it wasn't right' but some people genuinly have no idea. Like, I literally know two people who didn't find out until after several years of marriage that their husband was a pedophile. It happens.
I absolutely don't expect my s/o to actually be an asshole, but I would never trust someone enough to say that without a doubt. Both my and my partner are children from baaaad marriages/divorces, so I experienced the same as you
@Lomonossov and
@pachnik . I think growing up like that makes it hard to ever fully trust anyone. My parents divorce wasn't as bad as the marriage was because the kids were already adults, they didn't have any money but they also didn't have any debt. But my mother was a victim of financial abuse. My father would just raid the bank account as soon as the money came in and spent it all on himself and his toys until his balance was 0. My mother worked very hard and earned her own money, but it all went into this big black hole. My mum was the queen of frugal, she made more money almost their whole marriage and she had nothing to show for it when she got out.
My teenage and young adult years were full of worries. I struggled with serious illness, low income, I literally worried my father may one day kill my mother (that was a serious threat at that point, and I'm convinced he would have if he hadn't fallen in love with another woman right during the worst part of their divorce) and I literally had no one to help me out except for one family member who was only able to give me moral support, and she has passed since. I was always frugal, always a saver, and still I was stressed every month because I had to find money to pay the bills.
Having the legal documents that we have, is a form of damage control. If my s/o ends up being an asshole after all, that will be terrible, but at least I'm for example not liable for any debts I didn't co-sign for which I otherwise would have been. So I can at least get out with my own income, my retirement accounts, my emergency fund in my name only. I can start over. And I know that with the material things taken care of, I am mentally strong enough to handle the rest.