Yeah same here, every time we've met a couple, if they aren't knowledgeable on cuckolding, and they ask why she fucks and I don't, she always loves to tell them, i'm great at a lot of things, but hopeless at fucking, and that i'm a 'dud fuck' (a term she loves using on me) and that I always cum instantly. My ex-fiance used to love making me cum really, REALLY fast, and once 30 or so seconds became the norm, after a while thats all I could last. That was 15 years ago and i've never been able to reverse it.