probably a long shot since it's kind of a common theme, sorry not much to go on as well

the Uke is a virgin (for both gender. May get mention somewhere), possibly dislikes the seme or sees him as a rival.
Seme also knows uke is a virgin as well
Uke gets taken by seme one day forcefully and gets asked how is it to lose his virginity while being prepared
Seme been wanting uke for some time possibly. Not sure but possibly Seme comes of as a bit of an ass as well

also i think it was a part of a volume as oneshot or something

who needs drugs when you got yaoi