Hello, You are able to get a normal erection when you watch porn, think about women but you find it hard to maintain erection when trying to have penetrative sex. Your symptoms indicate more of psychological issue than medical. You are more worried about your performance hence triggering your anxiety. Stay relaxed take your time, do not get nervous, do not get unnecessarily stressed up. Stay away from any kind of depression (emotional or physical) as it may interfere with you getting hard. Taking oral medications help to maintain ED, you can take sildenafil (Viagra), tadalafil (Adcirca, Cialis), it is effective. Taking Ginseng is also helpful. You should take home made nutritious food, rich in minerals and protein. Take adequate sleep, stay well hydrated and avoid smoking, taking alcohol and any other addiction. Get clinically examined by a Urologist or a GP and get a complete health check up done to rule out any medical condition that may be causing you symptoms. You will be accordingly treated. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician