
Why should he doubt Jaekyung? He’s not stupid. It’s just that He doesn’t know Jaekyung is “fighting” over him with the other guy. He can’t even imagine that Jaekyung is angry, just because he’s jealous and possessive (maybe even Jaekyung himself doesn’t know, as for now. he’s such a jerk at the moment, but I’m sure he’ll fall head over heals for our Dan and he’ll make it up to him at some point). Plus, Dan has always been a bit on the naive side. How could he anticipate that Jaekyung would do such a disrespectful thing to him? Who could, in his place, figure out that something like this would happen?
Dan was stupid as hell for trusting Jaekyung and not double checking with heesung, that's a 30 y/o man right there