Here’s what works for me, weird as it sounds. I squeeze my anus as if I had to fart. I can do that as many times during sex as I need to, and after getting used to it I find myself riding an orgasm wave for a long time, as long as an hour or more. Physical fatigue becomes more of an issue than cumming too soon.
Using this trick I can come when I want. Sometimes my wife wants us to come together, other times she wants other things. She’s always asking me how I manage to do cum whenever I want, and I always imply some sort of Zen-like control of bodily functions. It works for me.
There is, however, a biological reason for cumming quickly. It has to do with our evolution, when we didn’t have the safety of a bedroom to make love in. I suspect the reason many men have a tendency to cum quickly is that those who came slowly died in the act, maybe eaten by a saber-tooth tiger, or hit over the head by a rival.
The reason men tend to fall asleep after sex, while women tend to get more awake, has a similar function. Assuming a primitive setting, the alpha male gets the girl first. But nature isn’t content with that, it wants some insurance that the woman will be impregnated. So as soon as #1 is asleep Alpha2 can deposit more sperm, etc.
Things tend to happen quickly in the wild, and sex is no exception. But just because we have a biological tendency doesn’t mean we can’t learn Zen-like control.