You can train yourself with masturbation. I used to masturbate a lot and had lots of problems with quick ejaculation. You become "trained" to respond quickly and with a lot of excitement and anticipation, so the same thing happens during real sex. I began using masturbation as a means to delay ejaculation. Set some time aside, and take yourself to a 7 or 8, and slow down, and back to a 7 or 8, and slow down, and back, and slow down, then go for a "10" and finish. Over time, I could masturbate for up to 2 hours without "popping".

BUT this sees sex as only a physical activity. Once I grew more, and grew more intimately in my relationship with a woman, and became more in tune with her, and with the ebb and flow of real sex in a real relationship, I could last as little as 3 minutes, or as much as 3 hours.

Slow down. Deep breaths. Take care of her. Relax. Connect. It will happen as it happens. AND some women, like mine, take it as a big compliment when I lose control and come too quickly. You can express it to her as a compliment after it happens (Sorry babe. You just looked and felt so incredible I lost control.) But then get right back into it! Go for the second round.

You are OK. Don't fret.