Implication by exclusion. There are a *lot* of pairings explicitly prohibited in the Bible. none of which are women and women. Know why? Because they had plural marriage back then. When a man married 3 women, that marriage did not represent 4 possible pairings. It represented 16.
But it's not just limited to Christian and Jewish texts. The Kama Sutra (A Hindu Religious text) goes into the topic headfirst with, among other things, its description of the "congress of the crow". It describes, very explicitly, how two women can make sure that they're both happy without having to take turns. You should really have a look at it, if you're truly as into religion as you claim to be.
Not only that, but hysteria was a common affliction for women, dating back to Biblical times. As you may know, the Apostle Luke (St. Luke) was a doctor. At the time, they believed women's emotions were caused by a parasite living within them, and that the various positions of the beast within the woman dictated her moods. The treatment involved a doctor manually attempting to convince the parasite to move, from within the afflicted woman. (I'll pause while you think about that for a minute). Women such as nuns, teenage girls, and married women were all "treated" for it, by doctors like St. Luke, or by (generally female) midwives.
So don't look at what AmyDB does with her girlfriend as wrong -- the Bible doesn't -- look at it as just a more creative way to emulate St. Luke, in treating her partner for an incurable condition, and showing her G-d's love in the process.