Most Helpful Guy
If it feels natural, if you're both on the same page, and especially if you're being safe/smart about it, I see nothing wrong with sex on the first date. It is a little faster than I typically move, but as long as I know she isn't going to immediately stop communicating with me or that if we are clear that it was only about the sex, I don't think I'd consider myself doomed.
Most Helpful Girl
Definitely not. I had sex with my ex boyfriend on the first date and we continued to date and then had a relationship. If it feels right, then it feels right.