So I'm lying in the dentist's chair this afternoon getting my teeth cleaned, when it hits me that I may be on the verge of committing an authorial sin I've always condemned in others. That's the trespass of having the plot depend on one of a loving couple, who have always communicated closely and openly, suddenly refraining from giving her lover a crucial piece of information, which lack of candor results in trouble, grief, mayhem, misunderstandings, and maybe even dandruff and the Heartbreak of Psoriasis.
What am I gonna do? It won't be a matter of letting him misinterpret something she's already done; rather, she wants to keep him in the dark about something she plans to do, something dangerous and daring and more than a little foolhardy. And she has to do it for my plot to reach its climax. How can I escape unspotted from the morass of stupid tropes?
Hmmm. I've been thinking about this the past couple of hours (happily, no longer in the dentist's chair). And I believe I can make it work by having her reason that she's keeping him in the dark for his own good because she loves him so much. She's got a strong protective streak in her . . . And she'll keep her mouth shut about her dangerous plans because she knows he wants to protect her, and if he knew he'd probably stop her. "Leave it to the police," he'd say, and ordinarily, he'd be right. But my FMC doesn't trust the police to handle it.
Ah, nothing like clarifying character motivations to get you out of Stupid Trope Prison. At least, I hope so.