What is Buddha's concept of unhappiness?

According to Osho, Buddha sees unhappiness (dukkha) not as life’s only reality but as a process born of clinging and avoidance. Pleasure and pain continually transform into each other; when we grasp at pleasure or resist pain, suffering results. Understanding this impermanence and dropping attachment dissolves misery. Thus Buddha discusses suffering to reveal the way beyond it—awareness, acceptance, and non‑clinging.