So Aya finally came to her senses and put an end to Sei's little fantasy play. Good for her, it was poison to both of them as neither was getting what they really need out of it. I have a feeling the author's still gonna put them together in the end, so it can now happen only by Sei getting her shit together and unfucking her brain.
Yoru's convenient arrival at chapter end gives me the impression that the finale may be near. Seeing that first two volumes had five chapters each, and next is fifteenth, it can be hypothesized that next is last, or we're still going to get at least one more volume's worth of disaster lesbians.