What in particular separates Section 7 from the prior two sections, and why is that significant?

Every one of the characters has a monologue in this section for the first time since they gathered to see Percival off to India. This signifies to the reader that the characters' existence as a single entity is perhaps returning. We learn that Bernard has left his wife, which was originally a very divisive moment, that Susan still feels for her friends, that Neville is beginning to let go of Percival, and Louis and Rhoda have ended their affair and come to accept their places in the circle.