It's the desire for happiness which is ironically more enjoyable than the perceived reward, and we spend all of our lives creating a preconceived idyll, something which we imagine we'll eventually possess, only we never actually get it. I'm guessing that what your feeling is the full consequence of realizing that you'll never find whatever it is that you were hoping for, or moreover, that it wouldn't be what you believed it was that you wanted even if you did manage to find it.
I had this experience, then I realized what was happening, how my mind had been tricking me all along. My expectation of happiness, of satisfaction, it was never something which could exist in this world. It's the longing for an illusory lost contentment which I never actually had, or the desire to obtain lasting happiness in the future, only that will never be something which I'll find by pursuing it. We perceive past and future states as more desirable than the present, or better than they'll actually be when we reach them to keep us striving, as happy and content organisms wouldn't live very long.
Eventually it became obvious to me that pleasurable experiences are only so because they either remove or lessen some preexisting urge, or relieve some form of physical or emotional pain. For instance, fapping feels good due to it relieving my sexual frustration. But would it feel good if I somehow had precisely zero desire for sex, if I didn't even want it? The reality of our lives is pretty sad once you truly realize it, how our brains constantly torture us. I mean given the right circumstances, punching a wall can feel legitimately pleasurable, but only because it's a good stress reliever, not dissimilar to every other form of agreeable experience.
So it's not really that life is supposed to be more satisfying, only that you're supposed to expect and believe as such to keep you alive, and to get you to reproduce. It's nature holding a carrot in front of you to encourage you to reach some futile goal. Lesser animals are the lucky ones in a way though, as they don't have the capacity to ever come to this conclusion.
