Massive plot hole at the end.

So the cops bothered this woman, tracked her down to her house, went completely out of their duties, just to tell her: "look madam, your daughter is being used by your friend as bait to attract a serial killer, which we don't think exists. So she's totally safe and in no danger playing tea in the park, there's our message, have a good day".
That's already crazy.
But it gets worse: said woman, heard such completely insane message from the police, instead of saying "my friend/boyfriend is bonkers, I'd better stay away from him - and wtf is the police up to gossiping like this?" she understands the police message as "my daughter is in danger playing tea in the park! Let me rescue her full throttle this second or she's gonna die!!!"

Look, the reality is that this is a stupid plot hole, the writer and director didn't think it through, they just thought "Aaron is gonna spy on him because he's fed up with his theories and he wants to believe they already caught the killer, so the case is closed and enough with this nonsense". His spying can only be "I'm gonna tell her that you are crazy". But they forgot that that is completely in contrast with the next scene, her being worried about said imaginary killer. She is on another page of the script, while the film reality has moved on to "officially there is no serial killer and Jack is a crazy clown". Only WE (and the killer) know the reality, everybody else in the movie, including Jack, officially know differently. There is NO slim chance Jack is right, the police must have been super clear on that one with her, or else they are not doing their job.