There are few things in life worse than wondering what might have been. A moment, an opportunity, dithering, worrying, the moment passes, the opportunity lost. Then years of wondering what would have happened, had the opportunity been seized. "Should I have been bolder? Should I have done something stupid?" Years of imagining that the moment is still attainable, running scenarios over in your head, ever more fanciful ideas. Futility and reality need not be a concern where imagination is required.
Then, years on, reality. A line is drawn, finality, closure. The opportunity will never exist again. The rabbit has bolted the net, never to be seen again; the one that got away, to be left only with a lingering lifetime of imagining "what if", dwindling away into a mere shell of a memory. A shell maybe, but that husk will never decay.
We move on; perhaps maturity is realising that most of life's daydreams are never fulfilled.