but when most of his interactions involve him scolding her and not!Peggy defending herself, it comes across that he simply doesn't appreciate her as a whole person.

Yeah, there has to be a visible element of mutual appreciation for me, otherwise I don't understand why these people are even spending the time with one another beyond the exigencies of the plot.

it's actually going to be tough to avoid in a situation like this where you have a by-the-book cop on one side and an amateur sleuth on the other.

The Penguin Pool Murder (1932) remains one of my favorite variations.