Some thoughts about the hightlighted parts:
Im thinking what were watching is in truth more of the story of Noel than the story of our MC.
So, hear me out:
I mentioned already earlier how i think everything (95%) of what happened so far is designed by Nael like that.
I imagine she became a long long time ago aware that her power would soon be too much to stay at this plane and that she would need a successor. She deemed non of the primordials worthy.
So she created Noel, a part/copy of herself but uncompromised by hard decisions, tragedys, experience and so on. She did something similar when she created the pact which enforces that dark ones "forget" (the memorys get suppressed) the tragedys of their past "life's" when their companion dies.
Nael started to exist and from Nael's pov shes simply perfect, herself but way better, purer, what she could have been without all the responsibilitys and tragedys.
So Noel was perfect in every sense, but she was not what Nael needed.
She was literally TOO pure for the role as Nael's succeccor, too good and perfect for a role which requires sacrifices and hard decisions.
Nael's power grew more and more, she was more than a primordial already and supposed to leave the plane. I dont think she stayed out of selfish reasons. She stayed because of Noel.
She kinda procrastinated, suppressed her own powerlevel to be able to stay and to be able to let Noel stay her perfect pure sister. Like that she was able to give Noel what she would have wanted for her own life, at least temporary, a sacrifice which we see repeated in the story by gabriel for his brother.
Nael was aware that Noel would need to change/develop at some point in time but she doesnt want a submissive servant like all the other primordials, she wants a equal sister and successor so Noel would need to want to change herself.
Which leads me to the point (sorry for wall of text): Nael needed Noel exactly at the point she is now, free and not bound to the pact anymore which could give possibilitys for incredible development and own will. But will lead to Noel uninveteablely experiencing tragedy and changing. Becoming more like Nael which is needed but not wanted.
I think Nael waited and needed a rulebreaker. MC was probably/maybe chosen because she became aware of him due to gabriels ability.
The MC was the bait. Something which Noel finally could want for herself.
She did let them bond in the first place, let them establish a connection but it was 100% necessary to break their bond. It was needed to enable Nael to gain free will on her own desire and by her own ability and to prove (for Noel and the MC) that their love is real and not created by the bond.
I think Ciarara will become the next primordial too. And in this case - again - i think Nael did send Cia deliberatly away when they had their private talk. It was useless as Cia is bond to them anyway and aware of it.
It was MEANT to make Cia insignificant but with the intention to push Cia's desire to become MORE, more important, more powerful and in the end a primordial.
yeah anyway, just my 2 cents