why does the author include the details about proctor adding salt to the rabbit stew?

The kitchen is empty when Proctor adds the salt to the stew. Later, when his wife serves him Proctor says "It's well seasoned". This delights Elizabeth. John is trying desperately to please her. The tension in their marriage is palpable. Elizabeth knows of John's extra-marital activities and John's own guilt is eating at him. His compliment is his own way of trying to heal the wounds.