There is a building feeling of suspense or excitement because Ylla has been dreaming about the arrival of the Earthman. She has that feeling that something exciting is about to happen. She, as well as the reader, is very curious to see what it will be. She seems trapped in a bad, dull marriage and her dreams add a bit of spice to her life. Her husband, who normally pays little attention to her, acts very skeptical about her dreams, but they really do bother him, and he clearly becomes very jealous. So there's a sense of mystery there, too--with the reader wondering about what he is going to do, because he seems to building up to something. If you have read the chapter, you of course know what he ends up doing.
