There were several all-lesbian sororities near the College. This was Liz's doing, of course.
While plenty of them had previously had lesbian members, as recently as ten years ago, there simply weren't quite enough lesbians in the Town with the commitment to making an all-lesbian sorority before.
Even the fraternities are slowly being converted by Liz's Bar. Some of these converted fraternities-now-sororities still accept male applicants (Liz's residual magic protects against awkward questions). But if current trends continue, then in the end, the Town will only have one technical fraternity left, and even that will only be because they were or are going to be transformed by a different bar.
The College's demographics were majority male once. Now, it is a majority female. It is unlikely to ever become an all-girl's school, officially or unofficially, but that majority is going to become an overwhelming one soon.
Not everyone who graduates from the college does so as a lesbian. Some graduate as robot girls, country folk, or snobs instead. About half of the graduates are still "normal" for now, but the numbers of those transformed by the local bars is slowly increasing, and those transformed by Liz have the highest numbers of all. The transformed are about to be the majority. In a few years, it will become everybody. The Magic Council's plans to create artificial new witches and forcibly reveal magic to the public are slowly gaining steam.
Only one of the sororities is officially advertised as catering to lesbians. A few of the all-lesbian sororities hold "initiations" to ensure the love is spread among everyone. Some of the all-lesbian sororities are only that way for now because of one incident and aren't really committed to keeping it that way, though new members are fated to be transformed by one bar or another.