Ik it sounds weird but there's a reason for it. It was explained further in the chapters, i don't specifically remember which chapter tho
It will look like that but if following correctly, it is not.
First Zenos and Mikhail are siblings, Abella and Mikhail are lovers, Abella died, and her reincarnated person is FL. It will only be considered incest if FL and Mikhail are in a relationship but no, they are not, Mikhail just wants to check on his lover who was reincarnated, and then our FL arrived. (that is the only thing retained in my mind, I may be wrong though).
If FL is the reincarnation of Abella, and she was also originally Zenos...and Abella was Mikhail's lover, who (Mikhail) was also one of the three children of God, doesn't that mean...incest?