First chapter 20, Sohyun said they have been dating a year.. Jaehee has been gone about year,,, and Hajin has been working about a month give or take. Jaehee is not together with Sohyun to get to Hajin.
I think he saw or thought he saw Hajin get up from the table because it was not that long before he was taking pictures of Hangyum and gave a dirty look when he walked off. No Jaehee doesn’t or did not (if he seen Hajin)
Chapter 25, He will text Hajin and ask if this is Hajin. If I remember correctly. Yes, Hangyum did that on purpose and they change his dialogue a little. Tapas made that a bit awkward, if I am right...... For my understanding of the Korean he did to get him Jealous. Some men wants to see the ones they like/love jealous. Hangyum would be one. We have known that since 7? Or 8? About his type of lover?

Seeing how the asshole checked his phone while thinking about Hajin, does anyone else think maybe he knows where Hajin is and maybe he even came back and got together with the girl because he'll be around Hajin ?
But if so, isn't it counterintuitive to face the person you want to get back with while having a girlfriend of your own ? But then again, that seems to be a common these in this seeing how the current seme did something similar in highschool creating a misunderstading on purpose....sigh what happened to good old "not being an asshole to the person you love" ?