Omg Yoonjae is such a little cutie pie!! And Yuri is a good friend to those two, giving them some alone time (': despite his grumpiness about everything
@ everyone confused: the kissing couple is Moogyeong and Yohan from the prequel For Your Love. They're Yuri's friends. Yohan was the one who let Yuri stay over at their house last chapter, and Moogyeong goes to the same university as Yuri. The girl on the phone is Yuri's sister, Kwon Yujun. Heeju, the cousin that Yuri's in love with, called Yujun while on her honeymoon. I think she didn't hand the phone over to Yuri because she knows about Yuri's feelings towards Heeju. He's worried because he thinks Heeju's husband was in a relationship with his former high school teacher (the other ML) and is swindling Heeju by hiding his sexuality. He decides at the end of the chapter to ask the "source" aka most likely his teacher.