Ok, so what the F is up with Jaemin. I was finally settling on the hypothesis that he just wanted to be friends…
It is confusing, i was so confused when i watched it a while back, what i got was that Jaemin loved (romantically but also obsessive) Da on from the start but he was aware of Da Ons feelings for Suyeon (in the past) and he wanted to ensure he didnt date him so J and S pretend to date instead, i think that S didn't want Da on to date J so thats why he agreed to the deal, i think S thought Da on liked J, and he didnt want them dating, so in a way they both did it for the same reason... my brain hurts writing this XD, don't know if that makes any sense. I felt like S unhealthy love type was very like... 'must keep him from all other potential love interests' but also he did not believe that Da on had any feelings for him when he da on confessed to J so he didn't want to date Da on because then he would break the deal or whatever and then Da on would then run to S, because to J, Da on still has feelings for S.