Question: People in my writer's group complain that my character acts like a nitwit. She takes stupid chances and ought to just go and call the police. But that wouldn't help my story at all. I write romantic suspense. She has to be the one to solve the mystery. What can I do?
Answer: Sounds like a motivation problem to me. Motivation is the reason characters do things, plain and simple.
You can let a character make any kind of foolish decision or take any kind of dangerous chance if you give them a good enough reason for the reader to feel as if they might have done the same thing in the given circumstances.
In a nutshell, to coin a cliche, that is motivation. Good characters keep secrets, tell lies, and take risks for good reasons. (Thank YOU Alice Orr, for teaching me that, a long time ago.) Bad characters keep secrets, tell lies, and take risks, for bad reasons. But they all have a REASON to keep secrets, take risks, and tell lies.
That reason is the character’s motivation. One reason writers of romantic suspense get criticized is because the dimwit heroine always goes blindly into the House of Hell that is obviously filled with weird characters and murderers, just because she is determined to solve the mystery herself, when any sane person would go away and be safe. If she does that go on her own, she’s an Idiot!!
Now suppose her baby sister is inside and the heroine has been told her sister will die if she calls the police, then she has a Good Reason to go sneaking around Hell House trying to find out stuff on her own.