What makes this manga realistic, at least this chapter, is how it shows that depression is a disease.
In any other story (manga, book, movie) the narrator seems to say that the disease comes from someone's fault, the fault lies with the sick person or the environment in which he lives, and then if a woman gets sick then the fault is surely given to her husband. Here they did well to describe in detail the background of their marriage, even if the two are not very affectionate, however, in their own way they love each other and despite the changes nothing excessively traumatic has happened. Depression comes and it's no one's fault, and it's also difficult for the family to immediately notice the symptoms or intervene, imagine that you are depressed and your spouse or mother always asks you "how are you?"