Hello folks! Just want to give my opinion of Nami's possible intention or pov. Based on the previous chapters, it seems she really like Seju even before. Maybe she's just on the sidelines watching Seju and Sumin's abominable relationship but she knows much to the point that Nami can even discuss the details of Sumin and Seju's past events. Actually if you'll look at the bigger picture, only Nami was able to pull of those well kept emotions from Seju. She was like tapping both Sumin and Seju to "hey come on guys be matured people and make a decision for your lives". Her sarcasm and approach to both characters maybe viewed as an asshole move but I think she really cares for the both Seju and Sumin and she's kind of more matured and deep character.