I wonder whether it's relevant that K comes across as consciously knowing that he's interested, and thus capable of reasoning about what he wants (and how to get it ethically and within social bounds); whereas B is acting on instinct and without awareness, so may suddenly come out with a proposition (or a grope) out of nowhere. If you aren't reasoning about your goals in a social interaction, your goal-directed actions may be rather random and unpredictable, which is bad for your partner.