For me it is needed to be known by our better half, but not totally as I mean only few of our wallets and some must remain private , we must have our coins safer with our husband/wife and we must have some funds outside of their knowledge.
this way we have back up in case the relationship did not end well.
I think that after getting married, the two of them are the most capable partners for both parties. I dont mind letting my husband know my mnemonic at all. Even if I hand over my wealth to my wife, I am willing to give her a sense of security. This is what I should do.
well that is a full trust that must be understood mate.