At the end of the novel, Joel has become an adult.  He takes responsibility for being the head of the house.  After Randolph nursed him back to health and he returned to the Landing, it is unlikely that Joel would want to leave. Below are two different reasons why Joel probably would not want to leave the Landing.

"The mature Joel ascends from the haunted garden at Skully's Landing to Randolph's room to embrace Randolph, leaving behind both his youth and his own sexual longing."

"Joel decided he liked being dependent. He felt Randolph was the only person who cared for him."

Joel has found what he is looking for, love and acceptance, so why would he leave.