Lost in all this is the DIL is immunocompromised, The condition recognized by the son & has been going on for 4 years.
Quote
"My DIL is immunocompromised and hasn't been to a restaurant in four years."
As a threat to well being this is an explanation
Why Immunocompromisation Is a Health Risk
Immunocompromisation is a way to describe a weak immune system. When your immune system is weakened, your body can’t fight off viruses, bacteria, or fungi very well. This can lead to serious infections and can pose a major health risk.
Many different types of immune system disorders can cause health problems. An overactive immune system, for example, can cause asthma, allergies, and autoimmune diseases, where your immune system attacks your body’s own tissue instead of bacteria or viruses.
Immunocompromisation is generally the result of diseases or medical treatments that leave you with a weak immune system unable to fight infections. Immunocompromisation is sometimes also called immunodeficiency.
What Does Immunocompromised Mean?
Whether or not the son tires of his wife's needs at some point IMO isn't relative to the "want" of the OP at this time. A need is something that is needed to survive. A want is something that an individual desires, but would be able to live without.
If it were possible I'd shake the hand of the son for caring for the needs of his wife. Forgotten to often is "in sickness & health"