Here's her saving some random ass Stalker kid, while her husband was being beaten half to death and proceeds laying like that on the floor at home 🥲
She can't rescue him cause then it would be too suspicious. "I haven't talked to you in years: how the fuck did you know I was brutally attacked during an investigation of a serial-killer killing our son's year classmates?". He already has some suspicion of her being the School Nurse right when these killings started.
Also, the dude called the cops/back-up (which is also why the bully ran away instead of fighting). People are coming to find him fucked up and provide emergency medical treatment.
Finally, give it some time. Usually stories like this will have a cheesy brief flashback where we'll see Mary actually come to his aid to make sure he's alright; but he'll be like half-conscious and delirious so he'll see her like a holy angel coming to his rescue. Cut to him later with a thousand-yard stare in his hospital bed while recovering, "...Was that really a dream? Was she actually there? Why would she be there? How would she have known? Do I miss her that much?"
Watch. Fucking calling it. It'll happen in like 3-5 chapters from now.