Whatever "it" is, will come back and bite you in the ass...

I've had quite a few moments where I've had my pride crushed by the great hammer of god's irony. The first instance of this I remember was at the GHA reunion some years back. At this point in my life I felt in shambles, I probably looked it too. While at the time I didn't notice it, I was particularly callous and selfish.
Then there was Catherine Goffreda. In opposition to my meotoric fall from the promise of my high school years and my obstinant hold to my "boyhood", she had become a woman. In the drama of that summer where I had first met her, she seemed like a sad character to me. She was enthusiastic, smart, and a contemptous overacheiver. Puberty had been rough to her and left her in a seemingly awkward transisiton between the girl of 10 and what I was looking at the day of the reunion. All that summer I had seen her been "liked", but not passionately admired.
The lession I learned that day and remembered with her coincidental reemergance into my life was that youth is something to be mourned with its passing, but only so much. It takes the time and scars of wisdom to appreciate the mechanations of your better judgement. So I find myself being grateful that I finally caught up to Catherine, or rather the icon of maturity she formed in my mind.

Why is it that in the end, all your ever left with appreciation for what you did and the doubt of what you didn't? Why do all the sorrows and joys that influenced you along the way fade?