from what i understand abella soul died that's why the fl (aisha) entered her body, but because the body is from abella ignis thinks that it is still abella and not zenos/aisha, the body is from abella but the soul is from zenos/aisha, that's what the prosecutor did when he killed aisha in her modern world and transferred her soul to abella's body who was already dead (without her soul), i know it's a little confusing because english is not my first language but i hope you can understand
It's in the latest chapter. Aisha's body is supposed to be the body Abella, the lover, is reborn into. But because of Procreator's meddling, instead of Abella, Zenos entered Aisha's body. But that body is already primed for the saintess Abella, so Zenos is able to use Abella's powers, but better, because of course Zenos is more powerful than mere saintess Abella. So because of that Abella's soul is still lingering, probably near Aisha since it was supposed to be her destiny. Supposedly that is.
So that's why after Mikhail aka Ignis knew about Aisha being Zenos, there's no longer confusion there. That's his sister. If they manage to kill Gaionia, Abella's soul will be free from her lingering and destiny, and maybe she will be reborn again and finally can be together with Ignis happily ever after.
Conclusion is, Procreator's meddling, Aisha is sister, not lover, and they all team up to kill the final boss.
this whole time I thought the FL was BOTH gf n sister? like old time sibling dating thing ☠ like I thought they were the same soul? where does it show that the gf/sister r different ppl?