I'm trying to outline a new plot and I had an idea for a motive for a crime which involves a woman secretly liking a particular man, being jealous and trying to get him away from another woman. It is a subplot to the main plot, which isn't about these people's relationships at all, but the crime IS part of the main plot as it needs to be solved by my MC, a ten-year-old.
I've been trying to think of middle grade books that involve adults in this way (one adult having a crush on another and it being a subplot) and the only one I can come up with is rather old - HALF MAGIC by Edward Eager.
Is this the kind of subplot that might put off middle-grade readers? Or is it just a case of how it's handled? In HALF MAGIC it all seems quite innocent and that's how I was going to try and handle it, but perhaps I should just come up with a different crime and perpetrator.