Wow. So many things going on here that guys have a hard time dealing with (see the Salon article link below.
I was definitely a nerd all the way through K-12, but I'm pretty sure it was a lot different back in the early 50's. Shy is shy I would think so there's at least some commonality here.
The essential element involved here, in my view, is the risk of humiliation. Smart, sensitive men tend to have significant imaginations. Not only can these provide for empathy to a fault, they can lead to over thinking everything before it even begins to happen. And in that is there unbelievably fertile ground for high fidelity consideration of all of the excruciating scenarios of looking like a clueless fool.
As a side to this is another aspect that I was particularly susceptible to. With such a huge imagination comes the ability to see too many things as you wish to see them. In that context, the behavior of ordinarily nice girls being cordial and outgoing, as any friendly person might be, can be blown way out of proportion as it relates to what you might interpret it to mean. This discrepancy, as it gets corrected by crash and burn results to overtures way out of sync with what the sender was sending, can tend to result in a person who comes to not trust his own perceptions when it comes to women.
My situation was a bit more unique in that I was also the product of an alcoholic mother who was both a mean drunk, and unbelievably perceptive of other peoples faults. If you had a weakness should could spot it and come back at you with it to take your skin off. As often happens in such dysfunctional families one of the children becomes the comedian to keep the drunk amused, and thus distracted, as much as possible; which is exactly the role I filled. I also had to become pretty glib and, at least sort of witty, to keep abreast of her perceptive abilities.
The upshot of all of this was that I gained the ability to be quite personable around women, I just gave up trying to determine whether they were interested in me or not. As such I was quite reticent in ever initiating anything other than friendly contact. This, in concert with the empathy, allowed me to have a lot of girl friends who liked being around me precisely for this reason. It is also why I have been thought of as gay on more than one occasion.
The other unique aspect was having a non-alpha male man as a father; one who also had this thing for being a salesman even though he was an amazingly technical person. The Navy trained him to be a full engine and air frame mechanic during WW 2, from which he transitioned quite well into the jet age. As such he could have continued making very good money with the airlines, or Boeing, but chose to rather be a seller of surplus aerospace parts instead. It was a choice that had him immersed in a sea of not only debt, because selling this stuff could be quite difficult, but also out in the deep of humiliation; a process for which I was made to bear witness of as he liked having me along when I was still quite young. It gave me a special appreciation for the characters in the movie "Glenn Carry, Glenn Cross."
I point all of this out mostly to give some feel for the complexities of what can go into making a man afraid to risk being humiliated; even though I know for a fact that hardly any woman ever knowingly seeks to have that affect when she corrects a mistaken overture. This is hard form them as well because they empathize too. They also have to endure the unthinking, not very sensitive guys who take their desirability for granted. That there can be a thin line between that extreme and the ideal of the balanced, confident man, doesn't help much either.
The real question is: What are to do about this? How are we to go about better socializing men to have a better sense of the duality of their emotional and physical make up? We are, after all, both women and not women genetically. Even more important, however, is the fact that, in both sexes, there are alpha personalities and non alpha personalities. Both sexes are put into difficult stereo typical role reversals when they are, or are not alphas. How does a man, who is not an alpha, not only approach, but live with, a woman who is an alpha. How does she handle having a man who does not necessarily fit the profile of a "trophy" man? Someone loving, giving, and even good in bed, who is otherwise not all that macho, or career/success driven? How do we instill confidence in men whether they are alphas or not?
We better start thinking about these things soon. And we better also realize that a good part of the problem lies lies in the overly competitive, abstracted, and disconnected, form of social organization we are presently saddled with. Such a system makes men just as much a stereo typical commodity, with all of the ridiculous behavioral and physical standards attendant therein, as it does of women. The two do, in fact, feed off of one another. As such this issue is just as much political as it is sociological. And it must be addressed as such.