
What people hadn't noticed is Nanjo might have started catching feelings towards Mokyeon and the signs can be seen starting at Ch17.
If he stops seeing Sunhwa, then Mokyeon might stop seeing him as well, so he continues the deal :) There's a lot of subtle signs since that chapter until the latest one. Currently he's most probably just confused as to why Mokyeon is acting weirdly so he'd rather they just fuck based on the contract so he can stop catching feelings towards a fuckboy (who he doesn't know is down horrendous for him)
See I told yall Nanjo already caught feelings long before this reveal
The moment he let him kiss him we already knew(づ ̄ ³ ̄)づ