She's not marrying him, it was trap for Asil cane out of himself so valrey can catch him easily. Her sister is marrying another guy Valrey threatened her to act like that way that's way she was saying sorry so many times because she was guilty for deceiving her brother.
Why she betray her own brother?
I just used Google translator for one ep where he got caught again, the raws are in korean and idk korean. So I have to wait for English translation.
Where did you get the raws???
Please don't tell me she actually wants to marry that asshole and betray her brother by letting the seme catch him