I am a 22 years old male.I am having problems whith my erection.When i'm whith a girl and we are kissing and touching i have a ferm erection but when we take out our clothes and prepare for sex it gets softer and softer.I started my sexual life at 16 and since then I had verry few sexual relations and that was the only time i had no problems whith my erection even though i could not ejaculate. I masturbate almost daily and do not have any problems whith ejaculation or erection when i'm doing that.I am physically attracted to the girls i'm whith.My curent girlfriend tries sommetimes to please me whith her hand but I cannot ejaculate and keep a ferm erection.WHAT IS MY PROBLEM??????