I'm wondering if there's yet another possibility? (please dig harder, m_a_a_ put your back into it).
Could απροφταστες imply πριν προλαβουμε να τις προφτασουμε,(νοερά) ... in turn implying the mysterious and elusive nature of the "window mistresses." (ειναι απιαστες/αφταστες)?
... να υποδηλώνει...