Taking on a divine mission often comes with a heavy personal price. For the prophet, carrying the weight of God's word results in deep loneliness, cutting him off from the ordinary joys of life and distancing him from the society around him.
Since receiving his prophetic calling, he avoids gatherings of celebration, laughter, and socializing with friends. There are different ways to understand this withdrawal. On one level, the word of God fills his heart with such profound spiritual and mental joy that he simply has no need for physical or social entertainment, choosing instead to remain alone in his home [רד״ק]. From another angle, his isolation is not entirely by choice; his very presence causes people to feel uncomfortable, naturally pushing him away from social events [ביאור שטיינזלץ].
As a result, he sits in complete isolation, much like a person mourning in sadness. The primary approach among commentators is that this intense solitude is brought on directly by the spirit of prophecy from God, which overpowers him and sets him apart. However, another perspective suggests that his isolation is born from physical suffering rather than just spiritual elevation. In this view, he sits alone because of the pain and humiliation inflicted upon him by the people, who curse and beat him in response to his messages [רד״ק].
This physical and emotional withdrawal is fueled by the overwhelming anger and harshness he must carry. Most commentators explain that God fills him with difficult prophecies of disaster, predicting the destruction of the Temple and the exile of the nation. The sheer weight of these terrible warnings forces him into seclusion. Alternatively, following the view that the people treat him with hostility, the intense anger he feels is a direct result of the actual pain and abuse he suffers at their hands [רד״ק].