how has the pearl caused the relationship between kino and jana to deteriorate

KIno becomes obsessed by the Pearl. Juana sees the change come over Kino like a shadow that envelopes him. Juan understands the power the pearl has over men's hearts. Kino becomes distant and abrasive. She tries to through it in the ocean but Kino catches her and beats her. Juana knows her husband is not the same man she knew before they found the pearl.