dude is she going to marry her own brother

I read some spoiler and yes he's the ml

Normally she will but, it's not her real brother she was adopted !!! there are not related by blood so if they don't see each other as brother and sister where is the problem???
Recently I read one, where the girl where her possible marriage partner were her cousins and uncle so ....(⊙…⊙ )

The cute boy's name is Johan but it the same they lived together during 5 years between her 8 to 14 and she said that she consider him more like a brother while Eugene dind't see her a lot after that.

I don't think she seeing eugene like a big brother because when she was adult she didn't saw them like a family and now they are accepting the fact that they are member of the family but to say that they see each other like real brother and sister I'm not sure about that. It's just a psychological problem so if in the end they don't see each other like that there is no "incest"