Theory of relativity, psychological version

Feel slightly better this morning. Or should I say "better for a morning"? It's always the worst in the morning.
We can put up with pain if we know it will be cured some time in the future, no matter how unbearable it may be or how long it may take. But the same pain is unbearable if we learn it will lasts forever. This mentality, I am afraid, is the cause of our unhappiness. When we are happy, we tend to throw cold water on it, thinking about the end of the happiness. This may be the reverse side of the same train of thought. A theory of relativity in a psychological version?
Why can't we value the absolute fact as it is without getting away from it? Why can't we face the reality? We are always distracted. We may need something unshakable and absolute to savor our lives in a real sense, whether good or bad.