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Soohyun likes Daon. He threatens to date Jaemin again because he knows Daon likes him (Jaemin) and will do anything to prevent that from happening. For example, he forces Daon to spend time with him saying that if he won't, he'll go to Jaemin. It's his fucked way of getting Daon to stay around him while also keeping him from Jaemin.
Jaemin on the other hand likes Soohyun but knows that Soohyun likes Daon. He's also aware about the fact that Daon has liked him all these years. He strings Daon along and manipulates him so that he keeps Soohyun from being with him.
It's a classic love triangle with Daon being fucked over by the other two.
can you all explain what's the relqtionship between daon, soohyun, and jaemin? who likes who?