Duhkha

Duḥkha , 'unease', “standing unstable,” commonly translated as “suffering”, “pain”, or “unhappiness”, is an important concept in Buddhism, Jainism and Hinduism. Its meaning depends on the context, and may refer more specifically to the “unsatisfactoriness” or “unease” of mundane life, not being at ease when driven by craving/grasping and ignorance. – Wikipedia

Duhkha is when you wish things were different. That wishing is the source of your unhappiness.

You see, it's now. It's always now.