The ''bestfriend' already knew that the family is cruel but she stills trying to marry into it and even blame the female main character [FMC] when she was just a victim as well (as she's being blackmailed by Gil's father in from of them all). The 'bestfriend' was so delusional that even if she got hurt by Gil's parents (mother pulling her hair and father poisoning her on the spot) but she was still fixated on marrying Gil just to outwit the FMC just to steal the guy she married into but didn't love him anymore.
I hope they remove the author's other work since it's not theirs, it's just having same name but the Japanese ROY have older works since the current ongoing is already from a remake..