To fix your problem, do the following:
1) get married before you have sex again;
2) after you're married, have him rub your clitoris to the point of orgasm or near-orgasm.

okay... so no need to be married like the guy above me said. BUT you definitely do need some foreplay. Me and my boyfriend were having this problem, but with a bit of teasing before the deed, we've managed to get it to the point that were cumming together. Another sugestion is, tell your guy to not use his "rhythm" right away. Get him to let you cum, then jump into the rhythm. That's something else we tried for awhile. Either way, it's all about sharing.

I agree more foreplay.Rubbing, kissing, licking, everything except intercourse. This will get both of you going. Then maybe put it on for a while for a few strong thrusts and then start foreplay or oral sex. This keeps him from coming too soon and keeps things hot. My hubby and I do this when I take longer, or you take him. Be on top and take control girl…get yours. By now you probably know when hes getting close that’s when you can pull out or stop. But sometimes its not about who cums and who doesn’t. After time its how much you enjoyed eachother…..like I cant come sometimes if I smoke pot and neither can Daniel. Or if drinks are involved our labidos are different. I get turned on really fast while he takes a little more work.. No need for either of you to feel bad about it. You are blocking your minds from the pleasure at hand by worrying about the end result.