I skimmed through the chapters to get an overall feel of the manga but uh, she's on birth control, right? No condom either? He didn't even bother pulling out. Hopefully, it was a safe day because it would be bad publicity to have a college model knock her up.
I mean, no big deal if it doesn't get acknowledged or not but I always like it when a person announces that they're cumming inside and/or it's O.K to shoot it inside. Telling one's partner directly about their intentions, and their partner accepting them, helps make sex scenes much more erotic.