Hi, I can understand your distress and the reason for your girlfriend s dissatisfaction. You seem to be suffering from premature ejaculation. It is a condition when a person ejaculates much earlier than desired which leads to dissatisfaction in sexual intercourse in either the person or his partner. Masturbation is a normal physiological process. Once a person becomes sexually mature, semen production starts which is a continuous process. A person the either has sex, or masturbates and has night falls. None of it causes any kind of problems. Masturbation doesn t lead to any physical or mental health problems. It also doesn t cause any problem with sexual performance, and potency and doesn t lead to premature ejaculation. Your condition is amenable to treatment. You should seek a psychiatric consultation for initiating treatment, which will include both medications and behavior therapy. Medications would include selective serotonin reuptake inhibitors like paroxetine (daily) or dapoxetine on as required basis. Behavior therapy sessions would consist of 1-2/week for 6-8 weeks. It would incorporate relaxation training, sex education and learning methods like squeeze technique, start-stop method and distraction. For better outcome, it is recommended that your partner participates in the behavior therapy sessions. Hope this information was helpful. Best wishes.