The Drake Equation, reapplied

Peter Backus, has taken the Drake Equation (an equation formulated to estimate the number of extraterrestrial civilisations in the Milky Way that we might come in to contact with), and reapplied it to estimate the likely success of his own amourous exploits:

While extraterrestrial civilizations may be rare, there is something that is seemingly rarer still: A girlfriend. For me. What might the approach employed in the estimation of the number of alien civilizations tell us about the number of potential girlfriends for me? A somewhat less scientific question, I admit, but one of substantial personal importance.