maybe I'm paranoid but I think she's not telling him the whole truth... even if she wants guwon dead, I doubt she doesn't have another hidden motif. but what I believe is: she actually wants to screw jinwoo over.
Additionally, Doc (I think it was doc who said this) mentioned how the hounds are crazy loyal to Guwon, and in the case that anyone were even to attempt injuring him, they'd be killed by the hounds. And if Guwon dies (unlikely) the hounds who are literally the ppl who provide the town with supplies, the town is screwed, bcs they'll have no reason to keep supplying the town
not to mention the chaos will be too much. the girl basically wants everyone dead and gone, in the end, because there is no way guwon's sudden death isn't going to impact the whole town, hounds aside. so yeah, she's either messy and suicidal, or has a bigger plan, which should include another charismatic figure who would be the next leader.
gurlie is being too short sighted here, she has nothing to gain with Guwon killed