Ezekiel's lack of mourning (Ezekiel 24:15–17) was a sign to Israel about their future. The Lord was about to take away the temple of Jerusalem, the place they cherished. God would desecrate it and destroy the sons and daughters left in Jerusalem.
On that day, the people would act like Ezekiel. They would not mourn publicly or perform rituals. Although they would feel deep loss, the devastation would be so great that normal mourning rites would be impossible. In such complete desolation, only internal grief would be possible.