The first time you go on night dating period with him, there's supposed to be a cock-blocked scene there (where after you take off both his clothes, Toru's mom will return home and become a cockblocker). Was that not the case in your playthrough?
Maybe I'm mixing memories, but surely the first time it was at Toru's house, where their parents were gone, they talked about putting the book to practice and so they did... It went to foreplay tutorial, let me remove all his clothes, and then do it with Toru all the way, then slept until morning... But no mother interruption in any moment.
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!