IMHO and Back In The Day, a guy could abstain without any *cough-cough* "preventative device" ... to borrow a line from one of my favorite movies, it's all about self-control and discipline. Also, WHY is Mio wearing nothing but an apron while she cleans the cage and Souma's penis? ... it's either a case of Gender Inequality, or she's putting him to a test.
And she seemed to like the result of a week of abstinence, she's going to put it on him again. Is It Worth It? You Tell Us, Souma-kun ... You Tell Us.
Well, I suppose that title certainly goes with the tags.
I'd imagine the catharsis after an entire week would be amazing, but it must be torture during said week...Next thing you know, she's going to suggests weeks or even a month of abstinence before having sex again.