The only way, the ONLY way, that Manabu will realize his feelings is when he learns Megumi wrote on his eraser. And she can't tell him, he has to learn it himself, either by seeing her signature on something else or while talking to Mikawa-san.
The sensei was nothing but a predator, and he smooth-talked Meguro into believing she could sex her way to happiness just so he could get it wet. Having learned that lesson, she applied it to a string of meaningless relationships with stupid horny boys until she met Koga.
I get the feeling...