My guess is that Haz is trying to dump him before he dumps her for the great girl his own age.
I could definitely be projecting Aya on her, but Haz also reads as very very insecure (she's an adult dating a teenager) and it looks like his attempt to reassure her that he's really w/ her for her (& not for sex) isn't working. I don't think sex would fix it b/c it's a Haz is insecure problem, but shrugs
i'm not even enjoying this anymore but i'm just OBSESSED~
from what i saw on anilist this whole thing has 10+ chapters to go so i'll stick around but omg it's so sadddd