2 things oft forgotten about pre-Code movies:
1. They can be pretty dark. Hays Code movies weren't just "no sin without punishment," they also insisted on happy endings. This ending's decidedly mixed, expressed beautifully in the closing line. A very different but even darker story, "Baby Face," is another good example of this.
2. What sex there is in this movie is - while unmistakeable to this grownup viewer - only implied, by language so indirect and subtle as to be safe around 1st-graders. The story arc is not (see 1 above).