Loyalty is an important thing, sometimes even people who are blood relatives betray you, so how reasonable would it be to trust your wife? My family consists of four members, son, a daughter, myself and my wife. At this moment, I have no choice but to trust my wife. My wallet has 24/12 words Seeds, and there is no other member to explain it except my wife. So I was forced to give my wallet Seed to my wife. I can't do anything if my wife cheats on me because right now I don't have anyone else to give Seeds to except my wife.
I think if you are living with a person and have spent years with them, you should understand how they are and even if you don't discuss it with anyone, keep inside, you should understand your partner very well and how their nature is, and that should allow you to judge them correctly whether they can do such a thing or not. After you do that evaluation, then you should decide whether you should entrust your seed phrase to her/him, or find another way to keep it safe so that it can reach your children when they grow up.
So many partners are worth being trusted because they do so much for you and they do it genuinely, but there can be some who might have two faces, one to show and one to hide, and such people can't be trusted. A person might be too good of an actor to never let anyone suspect them but I think if you are living together for so many years, you should be able to understand.