Why does marty sleep on the couch and does he complain?

we learn that Marty’s father is a mailman. He delivers mail to houses in the country and he travels about 85 miles a day. He delivers mail to 400 families. Although he works hard, they do not have much money. Extra money is used to pay for nursing care for Marty’s grandmother. Marty sleeps on the couch in the living room because the house is so small that there is no bedroom for him.