I know what you mean! I was re-reading this part, and noticed that to avoid emotional entanglement (though old Jolyon did take a big first step) the focus switches from the emotional to the material. I wonder if this is why the Forsytes focus on material things, since I do see little flashes of their unguarded nature, which they quickly close down. Here's a sample of what I'm talking about:

"What will you do with yourself, Dad? I suppose she's wrapped up in him?"

"Do with myself?" repeated old Jolyon with an angry break in his voice. "It'll be miserable work living here alone. I don't know how it's to end. I wish to goodness---" He checked himself, and added: "The question is, what had I better do with the house?"