Maybe we interpreted it incorrectly it's a given, though that this ends in a happy ending, but as I mentioned in my comment, this can go of both ways before we get to that happy ending there could be a time skip and it's because baek-hee will cut off ilwoo and maybe somehow someway they'll reconnect and or they'll run away together after putting it all on the table of what's happening in their plan initially before they met each other but gyeom we'll definitely go looking for him potentially with the dad or it'll be a set up

future Il-woo's narration said he regretted not killing gyeom so...what's gyeom gonna do?....the only thing I can think is that Gyeom goes fucking crazy removes any of that fake 'kindness' (him putting himself as a saviour) and threaten baekhee that he'll press charges against Il-woo and send him to jail.....(which I can imagine Baekhee being scared shitless since he thinks of himself powerless) and agree to leave Gicheon as soon as possible (or he'll have baekhee do something I can't think of) that's just the thing with abusers who are rich they get away with so damn much. No suprise what money & power can do for you
either way gyeom isn't gonna let Il-woo go even if Baekhee agrees....he's gonna have his revenge that's just the evil bitch person he is.