These two aren't even going out (technically) and they still fuck more than some couples in eromangas.
That is one aspect of manga I have always hated, where how often sexual relationships between people are just completely avoided and how we have entire series based around two characters and it never going beyond, say, a quick kiss by the time it ends.
You'd think with the whole birth rate panic that some in Japan are having (which most tend to either downplay or exaggerate) that there'd be pressure to have more sexual relationships in manga in some bizarre attempt to influence males and females into making kids. But, hell, even in manga where the plot does invoke the birthrate there still are rarely sexual relationships featured (again, outside of eromanga).