pheromone Syndrome (PS) = You get horny af if someone wants you.
Uke has PS. People generally don't like him so he's calm, but there's this weirdo (the seme) with bentos who really likes him... fuck.
Seme expresses love (wants him) so uke gets horny.
Seme follows after the uke, noticing his hard on. Uke is hard b/c the seme likes him (PS), but seme figures it's because the uke is into him and can't control his dick.
Seme jerks uke off and feels aroused at the sight, but figures it's because of his own PS. As in, because he believes the uke wants him, he feels aroused. That's why he brings up his medication and faults the uke for being into him, because the uke's strong want is affecting him like smh you businessman control your feelings.
Uke pauses, realizes that he actually IS into the bento seme and apologizes for inconveniencing the other with his feelings and a boner. He figures his own hard on has nothing do with PS because clearly the seme doesn't like him and HE'S the one that's mistaken and preoccupied and he's so sad--
Seme is a sadist and flips the uke over and fuck him. The uke's medication falls out, implying that the seme's desire made the uke hard (and created this whole scenario in the first place). Seme realizes this so they both reaffirm their mtual love.
TL;DR: Both of them wanted each other and mutually triggered each other's PS and banged in the bathroom. Bento seme is pretty egotistical and businessman is sad and insecure.
Drugless Sex