The Docs right, first though you need some space and just relax, take a sex break, be with your g/f and tell her no mucking around for a while, the slowly get back into things and see how you get on, but take things easy you have your whole sex life infront of you, and a good relationship will last a life time, me I got married 1970 and we still have sex now I'm out of ED.
Good Luck
Hello,
What you are facing is sex related anxiety. This usually happens in initial stages and the problem will disappear over a time. This seems to be absolutely natural. If your morning erections are good then the cause is psychological. Mean while you should take protein diet, regular exercise, remain stress free, and remove sex related anxiety. Talk to your partner openly about any fears or apprehensions, eat nutritious healthy food, exercise regularly and cut down on smoking or alcohol if you are taking it.
I sincerely hope that helps. Take care and please do keep me posted on how you are doing.