Kafka writes, "Gregor's father and mother certainly did not want him to starve either, but perhaps it would have been more than they could stand to have any more experience of his feeding than being told about it" (Kafka). The reality is, they are frightened of their son, and cannot bring themselves to accept what he has become, perhaps out of their own guilt for how they have treated him in the past. They take him for granted, and that is a sad reality. In conclusion, the story ends, "Just from each other's glance and almost without knowing it...

and, as if in confirmation of their new dreams and good intentions, as soon as they reached their destination Grete was the first to get up and stretch out her young body" (Kafka). This proves how little Gregor really meant to them, and how they simply used him to provide for them, never caring about his own happiness and well-being.
References

Kafka, Franz. "The Metamorphosis." Gutenberg.com. 2008. 11 Dec. 2008. http://www.gutenberg.org/files/5200/5200-h/5200-h.htm