ok.. so im guna cut to the chase

no trouble getting or maintaining an erection whilst masterbating
no trouble getting an erection during foreplay
comes to sex i lose the erection almost instantly with a new chick or close friend ive never doen anything with..
ex gfs who have been with for ages.. no trouble in sex department what so ever. its just on call.

thus performance anxiety..

now the question was is there anything i can do, dietary, or medication wise to help relax/calm me.. a lot of the times i do want to be with the girl or have intercoarse with her.. my brain says yes. my penis dies and says no. once its dead it can be got back through oral etc etc.. but come the intercoarse time it dies..

are there ways/methods to do to help with this. and saying 'to be calm' yes i know. but easier said than done as alot of the time i am calm and ready.. but its just not happening

jus wandering about diets/foods/drinks/medications that may help, etc etc.

ty