Thank you for sharing such an intimate problem with me; clearly it is causing a great deal of frustration for you and your new lady friend. I hope you don't mind, however being inexperienced in these matters, I referred your letter to my dear niece, who has recently returned from her latest honeymoon.
I'm sure you will find it comforting to know that it is, apparently, very common for men to become a little over-excited during a romantic interlude. My niece's advice is to indulge in a lamb shank just before you set off on your next date. I know that might seem a little unorthodox, but I'm sure a hearty dose of red meat will do wonders for your stamina. My niece said if that fails, try thinking of Katie Hopkins.
Hopefully that should do the trick, dear.