That's likely because banning consensual relationships is a incredibly poor attempt at fighting sexual harassment.

Allowing workplace romances inherently entails romantic advances between coworkers (some, or all of which constitute harassment depending on your views on the acceptability of asking out coworkers). If women are put off by these advances (as stated in the original comment to which I replied) one would expect that women would be more interested in halting this. But interestingly, women at my company seem to value the chance at making relationships with coworkers more than stopping advances from coworkers.