I'm gonna go on a little thought dump here...

I don't think that specific case contributes to the the cuckold fetish. I think a sequence of "experiences", could be completely non-sexual, that you experience when you are young develop COULD develop into a cuckold fetish. I'll share with you how I kind of went into this world.

I had a COMPLETELY normal childhood, was extremely well provided for, and have a good social life and yet I have a huge kink for femdom stuff (why? I still don't know). In my college life, I was close to a girl that I obviously had a huge thing for. I asked her out and she rejected me. COMPLETELY OK for me because hey its a numbers game and you can't catch them all right? Well, a few years later she posted pictures of her recent vacation on facebook..wearing a skinny bikini and hanging out with an extremely cut guy. She looked so happy and satisfied from that vacation. At the time of seeing those pics, I really didnt get turned on or anything, I just thought hey "good for her". Little did I know it planted the seed for the whole cuckolding kink. All that had to happen was accidentally bumping into the right cuckold video and boom instant turn on.

I view cuckolding as a sort of a category under femdom and thats why it is a turn on for me. It's kinda weird for me cause I like only a very small niche of this category where the video is 95% just interactions between the wife and husband. I don't get turned on by raceplay, the bull being better in some way or how big the dick is. All i care about is how the wife talks to the husband (mental/intellectual domination) and maybe some chastity play.