I realized that a source of unhappiness is expecting other people to do or say something without communicating with them first. People are not good mind readers, so you have to be clear about what you want and expect. I wrote more about it here: https://moviewise.substack.com/p/communication-insights-from... But the real realization is that you should not expect anything from anyone. You should be able to feel happy…
I had a similar realization, but it was a more generalized version of what you described. Unhappiness is what happens when expectations or desires don't match up with reality; if you want to be happy, learn to be content with the moment and what exists right in front of you right now.
On the other hand, one needs to dream, and hope--and that's what we should do. But leave goals and hopes for the future only, and don't hold on to failures, dwell on the past, or what could have been, or what is (whatever current reality you're discontent with).