Yiseul really isnt in a position to be interrogating Choah like this. Im not sure that she even likes Soyoung romantically or just platonically but its apparent that shes jealous that Soyoung wants to spend time with Choah in stead of with her, but honestly its not her place to decide who Sooyoung spends his time with. I was just rolling my eyes at her during this entire exchange. I actually would want her to work things out with Choah so they can be friends but doesnt look like its going to be that way.