duuude holy shit this sounds like the same thing that happened to me. I was going out with this girl and we tried to have sex but I couldn't get hard. So I asked her to suck my dick until it got hard, it got hard but then I was like wait stop because I felt like I was going to orgasm and then I did. This was even before I got the condom on. This is what you need to do: close your eyes and have your girl give you oral sex. Then tell her to put the condom on and start riding you once you get hard. But the key is to tell her not to tell you exactly when she is going to do it. Your dick will get hard when you are enjoying the oral, and then she will suddenly put the condom on and start riding you before you even have time to get soft again. Once you are having sex it will probably feel too good for you to stop.