xeks dont worry man. Everyone says that sex is mental for women and physical for men. Well, actually it is mental for guys also. Sometimes the pressure of having sx can interupt signals. When my mother was nearing the last few months of her life, my girlfriend then, wife now, and I didnthave sex much. I had alot of stress going on and sex just wasnt a high priority. If your really afraid there might be something physically wrong with you here is what you do. Take a roll of stamps and wrap it around your cock once before bed. If you wake up in the morning and the stamps have been proken, then your cock is working fine nd it is all mental. If you wake up in the morning and the stamps have not been broken then it could be something physically wrong, not saying there defiantely is, but I would then go seek the advice of a physician.
Side note, I dont know if stamps are sold in a roll any more or if they are always in a book. I would try your local postal office to see if you can get a roll. Also, make sure the stamps are notpulled apart before aplying them, this will defeat the whole purpose.