I don't really support this, couples hiding things from each other suggest a union lacking trust. I grew up to my mother knowing my father's investment and financial dealings and I'll not want to get involved with someone I'll be hiding my funds for. It really sucks and would be very de-energizing.
Yes, if found out that one partner is hiding some financial details from the other, it may cause some resentment on the party if the faithful one. In a marriage, you should marry your friend and someone you can relate things to, even your secrets, so what's the point hiding it? Unless of course you notice your spouse isn't as honorable as you thought.
If I have your seed phrases by mistake for hidden funds, since you had the mind to hide it. I'll be friendly enough to take half of the funds and leave half for you and I'll not agree I did it, after all, you didn't want me having any in the first place.
I have mixed feelings about it. Theoretically, marriage should really mean what you wrote in your post, but on practice things don't go as expected, as people may reveal themselves in a different shape than you firstly thought... One common solution is to marry under "separation of property" terms, so what is yours continue being yours during the marriage and in case of divorce.
However, what is the point of marrying someone, if you don't trust her from the bottom of your heart? It looks contradictory after all. If there is any level of mistrust in the air, it's better to just not get engaged at the point of marrying someone and committing yourself about living forever by her side.