lost the wood


So I had an opportunity to have sex with a 33 year old woman that attends my college and I messed it up. I was rock hard when we were kissing and she felt it. We weren't even intending to have sex but a couple of minutes later, I took off her clothes without objection. As I put on the condom, I started going limp very fast. The harder I tried the tougher and more elusive gaining my erection became. She was patient at first. But then she said that it was getting late and that she had to leave. She'll give me a fake smile when I see her on campus and barely answer my texts. I just want another chance to make it work. Any suggestions on how to go about this?

PS: I usually get a blow job right before sex but she didn't want to give a blow job