So Hata is pretty much stating outright that they have sex and he can't show it... and in fact, he can only show the beginnings of sexual intimacy in the extra chapters.
The whole thing threw me off at first, because I thought Nasa would at least be able to think back to the fact they had sex. Crazy that it can't even be "canon" that these characters are having sex. I didn't expect off-screen sex between a married couple to receive the same treatment as lesbian couples.