In Chapter 38, we learn all about the Guttingen family. We learn so much more about them than we have ever learned of Frederic himself, and this isn’t the first time we’ve seen this. We learn to much more about all the other characters than anything even remotely to do with our point of view character.
Frederic is just a traveler through his own life. He exists somehow as both the main character and a fly-on-the wall narrator. He’s like Nick in The Great Gatsby. He makes decisions, yes, but he mostly only exists to show off the other characters in the story. The only significant difference, of course, is that I actually like Nick.