Bill appears to be stimulated sexually by his visits the neighbor’s apartment, as does Arlene. Like her husband, Arlene too spends a great deal of time at the Stone’s apartment, rifling through their possessions.
It seems that Bill is drawn to his neighbor's apartment due to its sexual appeal, a trait shared by Arlene. Like her husband, Arlene often spends time at the Stone's residence, browsing through their possessions.