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.
You are right to worry about trusting someone even his wife with important information like your wallet seed. Usually anyone feel like he has no choice but to trust her with this information because there is no one else. It makes sense that anyone have to rely on his wife right now but it is also important to think about possible problems that could happen. Anyone might also want to think about other ways to keep his wallet seed safe like using special kind of storage or finding trusted company to help manage it. This could help reduce some of stress and risk that comes with relying only on wife to keep this information safe.