No, I never loose erection quality, unless I’m turned off by something. Even after I cum, I can continue having sex, with no waiting period or decrease in erection. In fact, if the orgasm is especially intense, I get more aroused and I get even harder. I can often cum, real orgasms, several times on one erection, if my partner can last long enough. Once we’re done, it takes 10 to 15 minutes for my erection to start to subside.
It sounds to me as if, when you get winded, it knocks your mind out of the mood, for a bit, and causes you to loose erection quality due to distraction. I’d suggest you exercise to improve your cardio health, so this doesn’t happen. You should alsdo try breath control. If you breathe deep and even, like during meditation, your body will not run out of oxygen and you shouldn’t get so winded, even if the fucking is vigorous for long periods of time.
Having enough oxygen in your body is important for any kind of activity. If you get oxygen starved , your body can’t function properly.