I blame the ease of access to internet porn. Young men are accessing porn on the internet from young age and from that, developing a totally skewed perception of what a normal sexual encounter looks like. Seeing overly well endowed guys pounding away at their female partners for endless periods of time, before swapping positions and continuing on. Only to eventually pull their cocks out of whichever orrifice it was last in and blow their load all over the women, mostly into the womans mouth or all over their faces.
I am sure that is what all of our sexual experiences are like !!!!!!
So young men feel that they have to live up to that unrealistic example that they have come to know as "normal",
It not just young men that are affected by this, women now are being subjected to a whole load of pressure to be instant porn stars, just begging for the guy to ram them in every hole and shove their cocks down their throats.
So yeah performance pressure, little wonder guys are turning to Viagra to enhace staying power and performance.