Harry's darkest times in Goblet of Fire all come when he's alone. When Ron isn't speaking to Harry and the whole school has turned against him before the first Triwizard task, it seems as though nothing can go right. Later, when Harry must face Voldemort alone at the end of the novel, he's absolutely sure that he's going to be killed. There's a clear message in the Harry Potter series that being alone makes everything worse. Whenever Harry is isolated – or when he isolates himself by trying to withhold things like his curse scar pain – all of his burdens seem a hundred times more dire.