I guess the first option is to involve your wife in the crypto world to an extent where she understands the basics and how to navigate wallets, exchanges and 2FA. Then if the worst were to happen she could follow (see below)
instructions: instructions are a good idea. do you have a safe place to store all your private keys and 2FA reset codes? Maybe you can legally file certain information with your lawyer or get a safe deposit box for this. (I still have my private keys in hardcopy at home but I don't have enough to worry about a safe deposit box)
As far as I can see it thats the only way while still staying safe from others and also from giving your wife access to everything now. Also forgive me but you never know when a relationship can go south ( and in my case completely out of the blue ) so the instructions in a safe deposit box seems the best way.