Responses
Remember that sex is a part of Jaekyung’s jinx and Dan agreed with their arrangement until Jaekyung can get his title back despite Jaekyung gave him an option where Dan didn’t have to have sex with Jaekyung as Jaekyung was still going to pay off Dan’s grandmother’s medical bills, which was the point of why Dan agreed to this arrangement m. Also they didn’t have sex for a while since that night soon after they reunited, there was a part in the previous chapter that Jaekyung held back even though he was horny because he knew Dan wasn’t in the condition for that.
So it’s not really about just lust.
Suddenly sex scene while we're having redemption arch? It feels out of place. Is it to show that the man still immaturely selfish to his desire despite his genuine affection towards Dan, or author want to pursue -physical intimacy brings two hearts closer- path, or what...? He's still a slave to his lust? Is it to show his certain consistency even amid his development?