I've always had some pretty special kinks about size comparisons, whether it's the height difference between a man and a woman, or the difference in sex size, and my kinks concerned guys who were really smaller than their girlfriends (so usually Futanari, or giantess). I used to explore this almost exclusively through hentai stories, sometimes just text without images (I'm lucky to have a vivid imagination).
The thing is, recently I started comparing penises online, and I experienced something quite disturbing. I'm not small at all, neither in height (190 cm) or penis size, and I've always gotten erections easily. Yet, when I see that someone's penis is bigger than mine, it excites me to no end, of course, but I immediately go soft even though I'm touching myself, and I ejaculate while being practically… limp?! And it happens to me almost every time, even though these are moments when I have rarely been so excited in my life! I don't know if this is normal, I've never experienced this before. Could you please tell me more about it?
(by the way, sorry for my poor english, I'm french)