Harry chooses to trust Thomas in Ch. 31. There are 39 chapters. I think that's to far from the end. There's almost a full quarter of the book left.And let me clarify what I was trying to say; I was a little vague. I meant a choice directly involving Susan. A choice to let Bianca have her, a choice to not tell her he loves her, etc. I'd say the choice to not trust Thomas is indirectly about Susan. It's a choice about Thomas based on what he did to Susan.