Switching the view of a character without warning, “seeing” or “hearing” things our they are not privy to, or switching from one type of point of view to another disrupts the flow of your prose and jolts the reader. Sometimes the reader isn’t even able to state what the exact problem is, just that “something isn’t right.” Always be aware of whose viewpoint you are in and why.
This is also the case with the theme. Once you select a theme for your story, keep it as the central theme throughout your book.