Its not that its needed af. They keep saying it bc the story is foreshadowing the pregnancy and they literally dont use any protection, plus the second to the last scene's. the seme let his liquid out on the uke. So its really possible that uke is pregnant. ┑( ̄Д  ̄)┍
The way everyone here has this weird notion that kids are needed in a couple. Stop promoting breeder mentality jfc