I think that they instinctively want a stable relationship, but many of them fight their instincts. It's a losing battle, only a matter of time before it happens.
I believe that lots do want a FWB situation in their minds (but deep down inside, they really don't). And I also think for many it's a phase they go through.
Either way, it probably won't last for a long time. Just enjoy it, recognize when time is up, and don't be selfish.
This. If you care about her feelings, you'll heed this.
By the way, in my experiences, alcohol is a truth serum. It's likely that she stopped holding back and let you know how she really feels when you got drunk with her.