Many men are very sensitive when it comes to p-v sex. If you would give your boyfriend a hand job or a b*l*o*w*j*o*b, he would probably last much longer. You could do this before or after he would do something similar for you, or you could both go into a "69" position. If you have to have p-v sex, he might last longer with you on top, facing him.
Practice makes perfect in this case.
Seriously. The more he does it, or the more he "relieves" himself (to put it lightly), the more it'll pay off.
Just make sure you let him know he's not a failure. that'll crush his ego if he feels that way.
Here's an excerpt from an email from Men's Health that I received that may be of use:
"Most experts agree there is both a biological and a psychological explanation for PE. If you climax too quickly, don't try to wait it out for the next great treatment. Use these tips:
1. Practice the start-stop method. Studies show a success rate of up to 95 percent with this technique.
2. Do yoga. In one study, men who practiced yoga for an hour daily lasted three times longer after 12 weeks.
3. Try to last 15 minutes when you masturbate. (This one takes practice to master, which is never a bad thing.)"
Here is more info on PE, which may help:
and here's a site with more info on what can be done: