When Jack yells at her, Wendy accepts it without fighting back. She clings to her faith in the idea of a traditional marriage, wherein the man makes decisions and provides for the family. Who is she to question him? Meanwhile, Jack takes out his shame for his decisions on Wendy, and blames her for preventing him from being successful. You could take the ghosts, telepathy, and haunted hotel out of the story, and it'd probably be scarier.
In the end, the movie is terrifying because it puts us in Wendy and Danny's shoes, making us feel trapped in a way that so many abuse victims do, with Wendy throwing herself in between the abuser and their child when all outside help fails. She's not Hollywood's idea of a "strong woman" (a sassy expert in martial arts and/or bladed combat). Instead she's a regular person who tries desperately to maintain some sense of normalcy, right up until it's time to risk everything and get the hell out of there.