I believe that it has to do with associating with me reduces her chance of getting somebody who she wants, so she wants to quickly dissassociate herself with me to make herself available to an opportunity if one arises.
Well kind of. 80% of men are invisible to women, you probably fall into that category to the ones that do that. Its most likely nothing really to do with immediate opportunity, its just at a glance she has already decided you’re invisible.