While having sex with my girlfriend she tells me that she hurts, she told me that from the first time we had sex, and I thought that I was going a little fast when I was inside her, and I asked her if I was going a little fast and she told me that this was not the case and she didn't explain it to me clearly, so at the second time, when I was inside her, I tried to be as slow and gentle as I could, but she was still hurting.  She told me that it was her first time having this kind of situation during sex. From that time we never had sex again. I tried to have sex with her but she was refusing. She said to a friend of mine which he is also a very close friend of her that I was no longer attracting her sexually.

I try very hard to find out what is going wrong and I get more confused as I try ,I don't know what to do, I feel that I am totally responsible for this situation and I can't do nothing about it.  Why she hurts? Can this problem be overcome?