Most likely not a concubine as the author did draw her in her past life in the magic mountain place that the story showed at the start.
https://kw-wcommunity-phinf.pstatic.net/20250501_277/17461070516653OHEM_PNG/%BF%AC%C8%DE%C3%B6%C0%CC%BA%A5%C6%AE.png?type=w900
It's established the medicine does change his personality so its not like yo il liking him is out of the realm of reason.
As for the car park dude. It's really up to the author how he'll feel about it. The guy is genetically a women so its not odd to be attracted even if you know their true...
Not saying that its going to turn into him romancing yo il, but typically that kind of development actually raises the chances of a romance because they actually have a reason to interact now.
Y
Yeah, I was kinda hoping for more too. Like maybe the boy she was trying to ntr was trying to screw her over or maybe the girl actually growing to like the guy. I guess im not the target audience for an ntr manga.
Kinda dont like the fact her whole plan is to screw over this one guy.