Through more than one circumstance of birth I have been forced on the proverbial path less trodden and I can't say it has been amazingly fulfilling. Of course, one can look at another and suspect how wonderful or terrible their life is, but that is all you have, suspicion. Friends who are married, friends who have children, some ... seem satisfied?
And then things go on and you become closer to the end of life than the start of it, more doors are closed than are open, and you wonder what -- if anything -- lies between here and the final trainstop, and if it is indeed worthwhile. You get a distant Peggy Lee "Is That All There Is?" detachment. The philosophers will tell you to assign some kind of arbitrary value and meaning and it is a bit like being thrown off of an infinite cliff and being told that you should assign the bottom of your soles as "h = 0" in that it lacks satisfaction as an answer.
I haven't anything to offer but a nod of recognition.