Is this the first relationship in which you've had these anxieties? (I assume from the post you've had previous relationships)
An alternative born from my own experience - that is, anecdotal evidence - is that if I think the other person isn't that interested, I am probably right. (The last relationship in which I felt that way, the girl in question got pissed at me when I cut it off after I decided she wasn't that interested. About a year later, she apologized, and admitted that she wasn't; she was actually still involved with somebody else, and had started seeing him again about the time I started getting those impressions. The tip-off was that communication which had been pretty much continual started lapsing; I'd get one response for every two or three texts or e-mails sent, and shortly after that she started delaying continually/cancelling every date.) I put off breaking it off for nearly a month, assuming I was being irrational and importing anxieties from my last relationship, which followed a similar pattern culminating in my catching her in a lie and the whole thing imploding rather dramatically.
So my suspicion is that you're not being irrational, you're simply responding to evidence you're not comfortable calling as such.
So my suspicion is that you're not being irrational, you're simply responding to evidence you're not comfortable calling as such.
I strongly advise against taking this advice in this particular instance. It constitutes some insight ("beware denial") and was a lesson that OrphanWilde needed at the time. However the overwhelmingly strong indication of Kenoubi's words (and also the correlated symptom "best two weeks of my life") is that Kenoubi is experiencing the oh so common effects of social anxiety and nerves that often comes when relatively little experience with dating. He doesn't need to be taking irrational fears more seriously.
I started going out with a fantastic girl a couple of weeks ago. Everything is great, except that whenever I've sent her a text message or email requesting something and haven't received a response yet, I experience significant dysphoric anxiety, fearing that her response will be not just "no" but "no and I don't want to date you any more". This is due to brain chemistry or personal history, take your pick—either seems like a possible explanation to me. But there's certainly no evidence supporting the idea that this is likely to happen, nor is the anxiety helping me prevent it or helping me in any other way.
Does anyone have evidence-based advice, or pointers to same, on dealing with this kind of issue? It is the only splotch on what have otherwise been the best two weeks of my life.