I love this manga but it's honestly not weird that asahi-sensei doesn't get a boyfriend if she's actively looking for one. She's to much of an open person that no other teacher or person she knows would fall for her. It's the same as with kuroi-sensei from lucky star no way in hell would bright, good looking and a little weird ladies like that end up single forever. I mean even male students would be after them, same as colleagues.