This could be a mental stress issue. Please consider holding off until you're married. Honestly, when you find the woman you will spend the rest of your life with, you probably won't have any problems making love to her. Don't get sucked into early sex, it really does effect you, and your wife is worth waiting for. Typically, masturbation doesn't prolong climax, it causes you to go more quickly. Again, hold on for your wife. God knows what He's talking about. You and your wife will appreciate it much more.