There is no such thing as degrees of treif. A cheeseburger without bacon is no less treif than a cheeseburger with bacon and what is true for the kashrut of food is also true for the kashrut of marriages. It doesn't whether these women "cohabit" with each other while being niddah- their cohabitation with each other is itself proscribed by halakha, regardless of whether they are niddah or not. #50 and #54 have the right idea. Reform and Progressive strains of Judaism would be more than happy to accept these women regardless of their lifestyle. For them to call themselves "Orthodox" and expect mainstream Orthodoxy to go against halakha by saying that lesbianism is not an avera is not only self-defeating, it's intolerant of Jewish tradition itself. And for the record, I really don't care what consenting adults do behind the privacy of their own doors. I only feel angered when Jews hypocritically discard their tradition, then post-facto demand the religious establishment to magically declare their lifestyles "kosher". This is not the way our tradition works and is merely adding insult to injury...

I have checked in the literature of Karaite Judaism, and Samaritan Israelites- neither group accepts homosexuality, whether male or female. Neither group considers the Oral Law or the Talmud to be binding. This proves that the understanding of Tanach has always been that homosexuality is a not a valid lifestyle- not male homosexuals and not lesbians.

Where does it say in the tanah that lesbianism is forbidden?

any traditional Jewish text that holds up homosexuality of any kind as normal, desirable, or acceptable. All relationships, except a few examples of bad ones like Sodom, are heterosexual. I think the message is clear, even if there isn't an explicit prohibition.

Are you a Karaite or a Samaritan? If you are neither one nor the other and still call yourself Jewish, then you are probably a Rabbinic Jew whose community holds the Talmud as authoritative. The Talmudic ban on Lesbianism is so closely derived from the Tanakh itself that, to make things short, it is considered as being a law written into the Tanakh itself and violating this Mi d'Rabbanan is considered violating a Mi d'Oraita. If you're going to reject the Talmud as authoritative, however, be prepared that you won't be lighting candles on Shabbat and Yom Tob. Also be prepared not to have electrical lights functioning in your home on those days either. Also, before the arrival of those days, unplug all your electrical appliances the way the Karaites do.