Theres methods to help this.

You CAN train yourself to last longer, so don't worry lil buddy!

I suggest reading over this, http://en.wikipedia.org/wiki/Prematu...tion#Treatment

One method is to jerk it, and when your close to climax, STOP. Its painful...but it will help you train yourself to get used to having to wait longer to climax. Theres other methods too, and methods that she can help you with too. They should list them in there.

Oh, also you can get yourself hard, then leave it. once it goes soft get it hard again and get used to being harder longer, it helps with ejaculation control.

Hope I helped, good luck, and make it up to her!