Do I need to read the main story in order to understand this one ?

no need to read the full story from the start, just pilsang jooeun scene are enough to know more about their first impression

Okay thank youuu

You can if you want to i read these chapters of this could from main you can also read them to understand this couple story much better -
1st story chp -30-32, 36-37, 41-45, 47, 50, 56-58

Thank youuu so muchhh