I'm having pretty much the same problem. Here is my story.
I broke up with my gf of 2 1/2 years on.... Christmas day, I didnt really want or love her in that way anymore. I also didnt want to break up with her on christmas, but I couldnt pretend to be happy with her anymore. The sex with my ex was fine, it was great, it was sex, I was always hard and good to go, pretty much.
Now its a month on and I have met someone new, she is amazing, i'm falling for her pretty hard and am very attracted to her, but last night we tried to have sex for the first time.... I just couldnt make it, I was so scared, nervous, I was shaking like mad. I thought it was some lube we were using at first, but we tried a couple times throughout the day, I got bits, but then I got worried about it or scared or whatever im not really sure, and lost it. I felt sooooo embarrassed, but she was good, she was very understanding and I told her how scared I was because I liked her so much, and she really likes me too, I want her so bad but even today, when I try stuff on my own I can barely get anything, and if I do its not for long, the second I stop touching it, the erection goes.
Im getting really worried and nervous about it and performing which I think may be the main cause, but im not sure if there might be another reason. When I touch my penis, it doesnt even actually feel the same, just kinda soft and inactive, like it is dead or something, I barely get any stimulation.
I changed my diet recently, I used to eat all the wrong foods but not ive changed all that and im eating great and working out, I drink eas myoplex protein shakes to help with working out and eating right. I dont eat alot of red meat as I used to, I used to eat loads of meat, burgers, steak etc etc but now its mostly chicken.
What can I do? Im not sure myself if there is anything I can do since it seems to me like a mind problem, I think since being on my new diet I dont have as much testosterone also, but im not sure.
Heeeeeelp, im so confused.