We may never really know what may be going through those doggy minds when they act this way, but I suspect that there can be various triggers. For example, perhaps he feels safer near your wife or he likes to sleep nearby her and senses you as a "disruption" to his sleep if you are often going back and forth through doors waking him up and startling him from a deep sleep or making more noise around the home, carrying tools, fixing things etc.
For mild cases, I use desensitization and counterconditioning techniques. For instance, I make sure that every time the husband moves towards the wife, the dog is fed some tasty treats. After several reps, the dog starts becoming more accepting of the approach because great things happen. How the treats are delivered may vary based on circumstances. I may have the wife feed them, or the husband may toss them in the dog's direction every time he approaches. These 'set-ups" are rehearsed several times until we notice a conditioned emotional response, where the dog looks eager to have the husband approach rather than dreading it. The process is similar to this: https://pethelpful.com/dogs/Help-My-Dog-Barks-When... but rather than entering a room, you are getting closer to your wife.
Now, a disclaimer is warranted here. While this procedure may appear simplicistic, it is not. In order to succeed, you will need to be careful on not sending the dog over threshold, you need to watch for signs of stress and you have ensure the safety of all considering that dogs who growl may bite. We do not want to push a dog to biting because we want a dog to keep "using his words" rather than biting. For safety and correct implementation, it is therefore important to conduct behavior modification with the help of a dog behavior professional who can provide in-person coaching and guidance. Hope this helps, feel free to post any other questions here or update on how things go in the comments section.