According to Osho, frustration after darshan arises because the meeting is a direct, personal encounter in which he "hits" you—shocking you awake and refusing to support your ego. The pain is the ego’s resistance to being shattered and pruned, not your true self. Understood rightly, these hard jolts are acts of compassion meant to trigger awareness and growth.
You feel bad after darshan because your ego gets a wake-up kick; it stings, but it helps you grow.