why my penis goes soft
I would have liked a bit more of courtesy in asking in full and taking time to give some more details as we are all doctors here giving our valuable time to answer your questions....but hey that's life, ain't it? The male sexual response cycle is made up of excitement (arousal and erection), plateau, orgasmic and resolution phase.  If you are having erectile problems, it could be because of many reasons...wrong or short sexual arousal (you don't like your sexual partner or whatever it is causing you erection in the first place etc.) or it could be because of some physical problems or could be the medicines that you are taking or many other reasons, depending on your age. Do consult a doctor if it is a repeating pattern. Good Luck.