While there are some missing pages in the Google Books preview, it looks like Wilder really thought of Baxter as sympathetic, someone who stepped up when the moment came to be heroic. He's at least willing to go along with the idea that the theme is "Be a mensch" (even if he prefers "When you're in love with a married man, don't wear mascara."). He doesn't think they'll last, but primarily because of money friction (what with him and likely her being out of a job).

Aside: he also reports that Fred MacMurray was attacked on the street by a former fan who claimed that he'd ruined "My Three Sons" for her by acting in such a filthy movie. (Maybe she'd missed Double Indemnity?)