It depends on the situation or personalities.
What if both of them are knowledgeable in crypto but have a different opinion on alt coins, or what if they are in a verge of breaking up?
It is good to have a partner with a similar mindset or have the same interest as you, you could both have your own investment or portfolio or just combine your investment to make it grow.
If they are both knowledgeable in crypto and have their own preferences, they can choose to invest differently, but even as that, they can still have separate investments and a combined one. Having knowledge of crypto can even make it easier, as they can use a wallet that requires both their permissions to make any withdrawal. Even in terms of going their separate ways, everything is based on agreement; they can split it.
Two good heads they say are far better than one, if the both have the same interest, doing it together can enhance the investment in terms of finance, time or attention given to the investment. However, there are couples who might not want to have a share of the same investment we still have to respect their own opinion on standing on their own rather than having a joint investment, if they can invest together is ok and if they can not it is still ok provided it is their personal decision and choice. But the truth remains that two good heads will surely supercedes one good head.
Two is indeed better than one, it is really just that there are those individuals who do have some trust issues despite of being married to other person on which they cant really be just that comfortable into the money that they are saving up and this is what i can say a little bit ridiculous but there are people who are really that like this. It is really just that too laughable that conjugal property isnt really that being applied or it isnt really been that considered by some couples or married person. Well, there's nothing we can do if they would really be having that way because its their money being saved and not ours. For me then i might consider out too on having some own savings on which that it is really that on my own and not being told into my wife. We do know that there are some needs that we do want to buy and doesnt really like on always asking for our wife to buy us with that. This is the main reason on why i do keep myself always having some extra fund but when it comes to investment or simply with my crypto holdings then its laughable that even myself do really comes up with this kind of idea. So it will really be that up to you on how you would really be that handling out when it comes to financial matter because in the end of the day when the family is experiencing some financial difficulty then it will be both husband and wife would really be coming up with solutions and this is where usually their investments would really be coming out when they dont really have any options or solutions into their problems. Separate portfolio isnt really that bad but it would be better that you should be letting your wife do knows or telling each other in between about your holdings since the budget do really comes from in between your incomes.