Sigmund Freud coined the term "penis envy" about a century ago, referring to a stage in a young woman's psychosexual development. He used it to refer to the anxiety they supposedly experience when they realize they don't have a penis. Professionally, I've never been a big fan of Freud but give credit where it's due; he certainly penned some interesting stuff. You can always liven up some cocktail parties when you bring up his name.
Cuckold porn seems to have a fascination with two things: First, the size of the bull's penis and second, the size of the cuckold's penis. Seems like all the bulls are hung like horses and all the cuckolds have clitoris sized members peeking out of their crotches. These size discrepancies help make the tales far easier to write, not to mention the excitement they generate among readers.
Let me try and size up the situations I've encountered in my own real life experience with couples I've played with.
I'll start by saying that my own penis is above average in size, both length and girth. It's not of gargantuan proportions, but it's above average and with only one exception, larger than any of the cuckolds I've run into. I don't make it a point to measure every cuckold's penis, but you'd be surprised to learn that the wives never fail to bring up their husband's penis size in comparison to mine. The size comparisons naturally follow.
Here's a fact: Not all cuckolds have microscopic sized penises. Sorry to disappoint. Their wives' biggest complaints? They don't last (premature ejaculation I guess) or "they don't know how to use it." The latter comment/complaint usually means the wives can't achieve a vaginal orgasm when their husbands fuck them. A woman has a better chance of having a vaginal orgasm the longer the sex lasts. So if the husbands (cuckolds) can't last...well, there you have it. Also, the ability to last has nothing to do with penis size.
Another thing, despite the notion that "size doesn't matter" that's been pretty popular in modern sexual circles, my own experience is that it does. Why else would the wives' I've played with comment on it? Like I said, my own is large, but not of biblical proportions. But when compared to the cuckolds', there's at least a "sizable" difference.
Invariably though, with every cuckold couple I've been involved with that has an element of D/s in it where the wife is dominant over the cuckold, cock size comparisons always come up. Not just in discussion but in actually putting the penises side by side. It's a nice way for the wives, and for me in some cases, to heap an extra helping of humiliation on the cuckold.
Janice had been a bit dominant over her husband before she was involved with me. Before we met, the soon-to-be-cuckold was already being kept in panties. So, on the night that Janice told him to pull down his pants, lower his lace panties and show me his cock while we were enjoying cocktails the cuckold had prepared for us, I knew I wouldn't be soon staring at "The Whopper." The cuckold was small, but not tiny. And amazingly, his penis grew as soon as Janice took it in her hand, held it, looked at me and said "See, I told you it was tiny." She called it tiny, and I later told her I'd seen some smaller.
Like other wives, Janice had me go through the drill. I pulled down my pants, lowered my jockeys and showed the cuckold my penis. Of course, my superior size was also the beneficiary of some previous attention Janice had paid it. With both penises on full display Janice looked at the cuckold and said "See, I told you it was big" and wrapped her lips around it. Both our penises got bigger at the sight of her sucking my cock. There I stood, inches away from the cuckold while Janice sucked me. As she sucked, I told him he could pull his panties back up and refresh our drinks. It was a great way to start our play for the evening.
Let me wrap up.....I know not all cuckolds have smaller cocks than their wives' lovers, but I think most do.
I'm no Sigmund Freud, but I think that those cuckolds with smaller sized penises suffer from a similar envy as the young girls Freud was referring to. This "penis size envy" experience comes about when the cuckold comes to the realization he doesn't have a penis of adequate size and stamina to please his wife.
It's a defining moment in the cuckold's psychosexual development.