@Kaarme
Well, Mayu's got stronger, but it's one thing talking to a schoolmate, another being confronted with a molester. Although, i too doubt author will reuse this situation.
Now, mother's obsessive ex is a Chekhov's Gun in a nutshell, given how she heard he was looking for Mayu (practically a stalker, so, yeah, statistics do get thrown out of the window). Talks about protection just lampshade the obvious. Don't forget, this is manga, so it's less statistics, more tropes.