Yes, this is the writer´s style, only for once it´s stretched out over multiple seasons. 

In all her dramas, romance is scarcely shown in-between a lot of different scenes (in Reply it was about the time period they lived in and specific events, in HP it´s patient stories or just fun banter) and hinted at but after one point, it takes up the main focus and strikes you. 

I think Ik-Jun and Song-Hwa is gonna be the same, probably initiated this time by Song-Hwa, since Ik-Jun basically, indirectly confessed to her and she basically indirectly rejected him for their friendship.