It is interesting to go through this experience of disillusionment. I’m old now, and I’ve gone through what you describe several times in my life. Everything always changes, all the time.

You might check out the book “Experiments in Truth” by Ram Dass. The audiobook is excellent, narrated by the author. He talks about how our mind will always be unsatisfied in its search for understanding, and he talks about how the wisdom of the heart is about loving and accepting. When the mind is out of tune with the heart, it’s a recipe for disillusionment. To quote John Prine, “Your heart gets bored with your mind and it changes you.”

Good luck!