After Haato and Toru-chi's first date as a couple, they went to his room for their first time. Toru comments that his parents are away for their anniversary and Haato comments that they should practice what was on the book (which, for the life of me, I don't remember buying; what book are they talking about and when did they buy it?). They went all the way without interruptions. I think it was the following day when Toru calls Haato over and tells him that his parents have resolved their issues and that they can continue without interruptions, despite not actually getting cockblocked in the first place. Also, after their first time, a default background appeared behind Toru's sprite, if that helps.
Thank you!