The obstensibly pro-circumcision comment makes my blood boil. You are in serious denial if you don't consider this as a factor. That said, there is also a big psychological component. I had trouble ejaculating the first couple times I had sex. Now I can go for as long or as short of a time as I want before ejaculating, total control. The OP said that he hadn't been with many women and/or not with the same one for very long. I wouldn't read to much into the delayed ejaculation. There is a possible reason that is very obvious: On some level, you are thinking "Do I really like this woman that much? Am I comfortable with the idea that I could have children with her?" When I started having sex, I had to tell myself "just relax, this is a good thing, nothing bad is going to happen". Of course having sex without a condom is much better, but your problem is probably mostly just a comfort thing.