If you’ll take some advice from an old guy..
Lots of men have been in that situation. The best way of dealing with it is to forget about yourself and concentrate wholeheartedly on giving the woman as much pleasure as possible by hands and mouth.start with a whole body massage as most women really enjoy it and it is also calming to give,.do it SLOW with long smooth movements. Then lie next to the woman with her in your arms and after lots of kisses turn her flat on her back with one of your arms under her to stroke the breast farthist away, put your mouth on the breast nearest and use your other hand to stimulate her clit. Most women find this kind of ‘three point’ stimulation very arousing and it’s more or less impossible for them to do themselves. After a while move the arm that is under her down so that you can use the fingers of that hand to hold open her labia for your main hand. When fully excited most women love to be held open and even stretched by your fingers.
If you really concentrate on her, you will probably find that you get a powerful erection. However, if you don’t/can’t get hard and she starts to want penetration then tell her that you are ‘having some nerves and things are not working’.if you have given her a really pleasurable session already then she will be very simpathetic and eager to try to arouse you,.at least she will be keen for another session soon and won’t give you up as hopeless, or worse;.tell all her mates what a washout you are in bed!