They aren't "abstaining".
Japanese women are notorious whores ( something like 1/3 have been involved with sex work by fucking HIGH SCHOOL ) who only want Chad ( to the point where if you're good looking there's literally well paying jobs where you get paid to just...hang out and keep women company ) and then "settle down" with a 6 figure earner who works 80 hour weeks minimum. Did I mention that infidelity/cheating is borderline socially acceptable over there? As long as a scene isn't made it's normalized.
Japan, South Korea, and soon the entire West is what happens when women have no incentive to pair off with the average man. The only thing women ever cared about men for was the resources they could get from him. Men care about women intrinsically. Women no longer want men because they can get the resources themselves. Men can't replace women as easily. This power imbalance is going to cause the collapse of society.