I don't think there is a need to create trust issues here because having separate accounts is more safe for both of them in every way those have already already said by philipma1957. So there is no need for both of them to adopt bitcoin in one wallet just for the sake of trust.
This may just be an expression of emotion, but in the long run, I think most of these will be problematic, even if they own a joint wallet by multi-sig wallet. Moreover, it is not the case that if two people hold funds in one wallet, they will get any interest. So I think it is better to have separate wallets to eliminate the risk.

We do agree on that, it's important to have separate wallets for both sake.
Love and trust your partner but do not put all your trust on them, don't be fooled by the display of honesty from any partner, even family are threats to your portfolio, always be active to know what to agree jointly and what to do separately.
Having a joint portfolio isn't a bad thing, there is a way were the wallet can be secured, both partners needs the attention of the other before being able to withdraw from the portfolio, shared wallet can be a preferred option for the partners. They are also free to own different portfolio outside the joint wallet, don't put all you got into one basket, it may fail at the end, learn to diversify your options.
We're seeing in the world how partners are ending. Left and right divorce papers are being done and that's why in terms of assets, we have to separate them.
Trust no one as they say.
What I'm thinking is that if they get angry and talk about this with their husbands, it's probably a lot better than if they do the same thing in silence. What if wives also started to build their own plan B? They will start neglecting housework and children, and look for ways to earn money to build their own savings and investment fund just like their husbands are doing. That will cause family happiness to begin to crack and breakup is inevitable. If the husband can do it, why can't the wife? Has anyone thought about this?
Yes, many men here have the same thought about having a separate account, but I want to know, are these guys married or never married? I would be surprised if any girl married these men when they knew what kind of guys they were.
For both ends, there is an equal thought.
But I think it's because more of the burden are placed on men because we're the breadwinners. And you're right, if men can do what we're thinking, women can do it as well.