Practice makes Perfect... As cliche as it sounds.
(1) Remove your mind from the act of sex to keep from ejaculating so quickly... By that I mean, think about something besides sex while you are having sex and you will not get so worked up so fast and climax will be delayed.
(2) Masturbate over the course of one hour, and don't let yourself ejaculate... Learn to control the moment of your ejaculation.
(3) When Masturbating, as soon as you ejaculate, continue to masturbate so that you don't become flacid. Most women don't care when you ejaculate as long as you stay hard to continue the sex until they get off at least once preferably two or three times.
(4) Use the techniques you've perfected during masturbation on your spouse. If you feel yourself starting to ejaculate to early, slow down to hold it in. Or if it's to late, speed up to maintain hardness.
Most of Sex takes place in the mind... control the mind and you will control the sex.