Age 17, I've been having this problem for quite a while now. Since I have no idea what's really going on and am really worried, I am going to be completely honest. I started intercourse back in seventh grade. (I'm a junior now) The entire time I've been having sex it was always with the same girl, never another. Back in November this year i entered a relationship. This girl is cool pretty and I'm really attracted to her. We spent some time before we got into sexual activities. We make out and hold each other and I just can't seem to hide my erection. The first time I wanna say we tried was like two months back, maybe a little longer. Everything was going good until we took off my pants. Immediately I lost my erection. This freaked me out. We kept kissing and rubbing hoping it would budge. She even went down on me and I gained an erection(not sure if it was full). Then we tried to put it in but it hurt her so I pulled out and lost it again. I used to be able to get an erection at the thought of sex. Now it takes masturbation, and at that it's never full. Plus it won't just stand up high and mighty like it used to. This has gotten to the point where it's really depressing for me. But a week or two before me and my gf tried to have sex I had sex with the girl I mentioned earlier. I still remember it I was hard as hell for her. The only way you could get it down was by taping it to my leg or something. Maybe I should throw in the fact that this girl had a way more physically attractive body. The same thing was for this girl we'd kiss and cuddle and I had an erection and when it came to sex I never failed. And we had sex a lot. That's why I'm so freaked out about why I haven't been getting hard. Now every time we try I'm just nervous about it not happening. End up disappointing me and her. She doesn't say but I know it. Please any one help we are willing for almost anything.