There's a bit to unpack here. My mom has been divroced twice, my dad once, my step dad thrice. I'm no stranger to any of this, and that's also what has shaped my view: in the six bloody divorces I got to be a part of, the assets were cut and divided regardless of who "held" them.
A large portion of posts on this issue centre around the "I don't want to have to justify where I spend my money" schtick, which I find interesting because:
A) Yes, you absolutely fucking should and do.
B) Your partner shouldn't give a shit assuming things are as they should be
I want to know where our money goes. We have a budget and I want to make sure we stay in it. She has the same mind. It's all good. If you aren't in alignment, then sure, I can see why you don't want to be judged about your money habits... but I think there's now a broader argument there. Are you with the right person?
My wife and I don't differentiate her money from mine; it's our money. I need her doing her thing in order for me to do what I am doing, and vice versa.
Every month after the books are done, we decide how much we're going to spend and how much we're going to save. This ensures alignment.
It's been working well for us for the past 7 years