Serious reading is hardly a social activity and every halfway serious reader is perpetually subject to a form of coitus interruptus. Family members or friends who lack the desire, the courage, or the opportunity to burst in on you when there's some indication that you could be sexually entwined will seldom hesitate to interject themselves between you and a page, even though the act of reading is often as intimate and intense as a full-fledged carnal embrace. You must take steps to ensure your privacy.