People watching

I'm a people watcher. I watch humans with the detached observation and avid fascination of a seasoned bird watcher. See their mannerisms and predict their temperament, observe their behaviour, inhibited and no, and understand how the two differ. That said, I am, and my goals are, something else entirely from that of a bird watcher. Humans gave up their beauty (for the most part) in exchange for psyche, and their idiosyncracies and subtleties and lies make them far more interesting.
I like to watch couples, too.
Most of the time, my first instinct has been to imagine them having sex. It seems like such a natural thing to do, imagine them, naked, sweaty and in the throes of passion (or disinterest) because that's the most natural thing to do. Next to shitting, eating, breathing and killing. Fucking's up there with the most natural acts.
Also some people I try to imagine shitting and it just doesn't work.
But now, there's something different in me, and I've started to question why. Why is she with him, and/or he with her? Are they just compatible like that? Does she like his cock? Is that why? Or does she resent it? Is it money, is it security, is it for the children? How have children changed their love? Is she loose from childbirth? Was she always? Does his prick lose its spunk after the first round, or did it always? Can they still look each other in the eyes? Did they ever?
Does he still find her attractive, and her him? If so, why? If not, why? How much of her has changed more than he in the years? Is he in any position to judge her, and is it reasonable for him to peruse dark streets for fairer fare if gravity has taken its toll?
How different is sex now from when they were first lovers? Did they have that young, awkward fumbling of passion? Or that slight innocence and tenderness in their post coital gaits, hands intertwined and shy, mischievous glances exchanged, as they walked out of a dark theatre, a parent's bedroom, or a hushed night park? Or did they meet, both seasoned lovers, with deft hands to unzip trousers, unclip bras and grip flesh? Was there an imbalance in skill; was it he or she that was nervous and whispered in ears, tentatively, "be gentle"?
Now of course I could never ask anyone these things. No one I don't already know well enough to know the answers in my heart of hearts, anyway.
It's not a perverse thing. It's mere curiosity about a natural act we've accosted with taboos. Will you judge me if I ask you how you breathe, and if you breathe the same you did when you were young, if you still have that childhood asthma? If you can remember how you inhaled sharply when you first saw her, and caught a lush hint of the smell of her hair, a smell you would be determined to have in your hands while she slept, naked, curved into your body?