What chapter 2nd couples story starts ?

their story starts properly in chapter 49 but you should read chapter 21 when they first met and chapter 26, 27, 28 is when they first have sex.

also chapter 33 to 36

the relevant chapters are:
14, 15, 16, 21, 22, 23, 26, 27*, 28*, 30, 33*, 34, 35*, 36*, 42, 43, 44*, 45*, 46*, 48

Sub couple chs might have minor spoilers: 16 they meet iirc 21 asks for eunhos info and sees him kiss another guy 23 warns main bottom that eunho seems suspicious 25 eunho asks him out to drink (and super tiny bubbles saying his face is his type wtf) ch 26 they go to hotel first time lol. Lies that he’s not a virgin, 27-28,33-36, 42 sad, 43-46, 48, 49-51 and pretty much the rest of s3

Tysm