wait wait wait, they're newly-weds and it has been how long since they last shagged? !
Gotta be at least once per day when you're that age & that new in the sexytimes novelty phase living along, right? Christen every room, do it in the shower on shark week, etc
(IIRC they didn't shag pre-marriage and not for quite some time after it too for some bizarre reason)
Is this super low libido thing meant to be normal in Japan? Cause I've seen similar newly-wed couples scting like they've been married 20yrs in other manga too.