What evidence points toward the conclusion that Gregor Samsa's family had been leaving him in isolation?

Though Gregor Samsa is not sure about his family's attitude toward him, a reader who pays close attention will conclude that his family had been keeping him in a boarded, locked, and empty room. The only reason Gregor Samsa had escaped his room was due to the fact that he went out of his unlocked door before the locksmith arrived to fix his bedroom door. There are boards up against the only window in Gregor Samsa's room and there are no furnishings inside his room, though all three other rooms are said to be comfortably furnished.