I'm one of the strongest privacy advocates on this forum, but at some point, this just becomes common sense to let your spouse know. Why would I want to risk me suffering from memory loss or dying and none of my family being able to access or benefit from my bitcoin? My wife is fully aware of all my wallets, all my back ups, all my security, etc. Why would I want to keep that from her? If you are having so many doubts about your relationship that you think you need to keep a large part of your finances completely hidden, then you should have signed a prenup.
I share the same opinion, I mean if you don't trust your spouse then who do you trust? Since, you've picked them to spend your life with presumably. Memory loss is a real problem to contend with, and statistically a lot of us will develop a certain degree of it, whether or not it'll get bad enough that you lose complete control of it is another thing, but it definitely isn't the risk.
However, it comes from a trust point of view from me. I'd trust my spouse since I've let them in my life. Same as children, it would be completely selfish in my opinion, to have Bitcoin stuffed away in secret, and not have a way of getting your spouse or children that money.
Personally, I see certain people in my life as an extension to my security, and by that I mean they can help you if you ever lose access, whether that's through memory loss or sudden life altering accidents. They are the one's you can rely on, and therefore instead of compromising your security they enhance it. Obviously, you have to be sure you can trust them, but if you can't trust them then they probably aren't part of your daily life in the first place.