Responses
I'm pretty sure Minyoung has feelings for Joohee, or might just be possessive. Maybe after Joohee got her heart broken and swore off relationships Minyoung saw an opportunity to keep her by her side without fully committing (mentioning the other hook ups might be her way to get Joohee to feel something), but then Heesoo came along and completely changed the game.
Off-topic, but I wonder if we're ever going to see what's up with Minyoung (Joohee's friend with benefits), why is she so adamant on not letting Joohee stop their arrangement?? Everytime we see her she mentions some new hook-up anyway so what the heck.