Does the rest of the script take some action based on the contents of the form?
If so, you need to take control over the bigger script and do something like
if ($_POST['submit'] === FALSE) {
include('Submit_reasons.php);
} else {
DO STUFF THAT DEPENDS ON A COMPLETED FORM
}
Remember that PHP is a server-side scripting language. It cannot really be told to "wait" for the user to do something.