Alternative - my partner and I (and also two other close contacts) have password managers that contain each of the other one's secret. This was less an effort to help with the memory loss scenario and more of an effort to deal with death and access to services (especially to cease subscriptions and the like).
In a lower trust scenario you could probably use a lawyer as a broker of the secret (potentially even as part of a will).
this is honestly a very pragmatic solution. the amount of life-long relationships i've seen vanish overnight has got me to reconsider my choices when it comes to single points of failure.
I like the idea of the lawyer, unlike normal people, they like sticking to their promises.
Password managers like bitwarden also have emergency access features which can do this, with the caveat of trusting them to enforce the requirement of access only being granted after a notification to the account holder is not denied in some time period (but unlike the lawyer you're not trusting them with the secret directly)