Why is it a relief at lunch on September 10 when Will's friends help themselves to his food?

Ben helps himself to a handful of fries from Will's tray. Ben's bad manners are a relief to Will. For a long time after the accident happened, even Will's best friends had acted differently around him. They would not grab the food of his plate. They did not tease him. Having Ben be so casual made him relieved that they were not treating him special anymore because of his father's death.