That's a loaded question Switch to almond milk and have him do something called the Emotional Freedom Technique (Natural), buy exteneded pleasure condoms (Chemical), or have him do root and sacrel chakra exercises (Metaphysical). Not a good idea. It could damage the penis.
In response to your question there is a array of things you and your partner can do in efforts to increase you stamina during intercourse. I would first like to start off by saying that stamina has a lot to with the mindset and timing of your partner. Now, lets talk about the mindset of a man leading up to and during sex. It can simply be put “ OH MY GOD IM HAVING SEX AND IT FEEL SO GOOD. OH MY GOD PLEASE PENIS, DON’T EJACULATE YET!” Essentially all men are basically riddling their brains with whatever outside stimuli they can think of other than sex so they don’t lose it or epically fail in a record amount of time. You could possibly comfort your man in telling him everything is ok and going back at it again a little later once the refractory period is over and your significant others penis is a little less sensitive. In my experience I like to think of a movie I just watched or plan out my day. This may seem a little rude or inconsiderate, given the fact that you’re engaging in sex. But if your having trouble with premature ejaculation trying something is better than nothing. Another thing I may suggest would be having your partner take it easy and not rush things. There may be a point where you guys may be getting into it and the speed of things starts to pick up. Tell your boyfriend its ok to pull out and reset. Just incase he feel like he is going to spoil the moment. Based off experience Getting ahead of you is one of the biggest key contributors to premature ejaculation and I have to remind myself it’s not only about what I get out of it.
If he ejaculates too soon, it can be caused by several reasons: he is very excited, his penis is hypersensitive or he has premature ejaculation. If the reason is a physiological disorder he should ask for the medical help. Maybe, he needs to take certain drugs. Such enzyme inhibitor as Dapoxetine is used in the chemical formula of drugs for the treatment of premature ejaculation.