Considering she's a sadist, the best thing to hope for is that she doesn't turn into a Yandere after getting the D. Lumi's already possessive, but not "Imma kill any bitch that touches my man" possessive, scythe girl might decide she's going to be the only one mating from now on which could lead to... complications.
As for the childhood friend becoming the deeply jealous god after being dragged out of the window seems unlikely since that would make a paradox. Without the DJG, Youta doesn't get dragged into the world and start mating with other women which means that he doesn't mate with Lilia which means she never goes to the real world to toss him out of the school building in the first place. Then again, if Lilia was able to become a witch somehow in the original universe that started the loop I guess it would be possible. The problem here is that it would make Lilia too obvious if they did that sort of plot and knowing how Okamoto likes to operate from his other series, it would be a "twist" and Hanahana would be the DJG, not Lilia.