This is particularly true if I have an attraction to someone, because my feeling of attraction is tightly coupled with unacceptably strong fear, shame, and self-hatred so that I become exceptionally false and not "present".
Okay, interesting theory. But what's the mechanism here? One theory is that the problem lies in the 10th cranial nerve. This is the vagus nerve, which goes to both the gut and the lungs from the brain. The "polyvagal theory" holds that separate branches of the vagus nerve, when stimulated, produce strong and opposed feelings: either you feel very safe, or not at all safe.
This has implications for a number of problems, including some autistic spectrum disorders, PTSD, panic attacks, and social adjustment problems. If the two systems become, as my therapist puts it, "overcoupled", then it can be impossible to make a serious connection with someone without being overwhelmed by unpleasant emotions. The result is a kind of neural shutdown, which makes people like me seem distant or standoffish when we're feeling exactly the opposite.
Stephen Polger, the originator of the polyvagal theory, has had some promising results at the University of Illinois treating autism with sound. There are also some suggestions and tips for dealing with these problems in this interview with Polger, which is intended for a lay audience. The other information I've found about this so far has been much more technical.
In my own case, since I am not autistic, PTSD, or suffering from panic attacks, the goal is to get the neural function more normal through a combination of neurofeedback, EMDR, somatic therapy, and medication. It's kind of a science project though, since some of these ideas are very new and raw and will undoubtedly be further refined later.