Post Full Text Linked Issue

I am having this issue with a wordpress theme.
The full text of each post is always linked as a whole back to the index page. Here an example: https://bit.ly/XcqxZI

SINGLE.PHP CODE_

<?php get_header(); ?>

	<div class="content">

	<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

		<div class="post_inserat" id="post-<?php the_ID(); ?>">
			<h2><?php the_title(); ?></h2>

			<div class="entry">

				<?php the_content('<p class="serif">Read the rest of this entry ?</p>'); ?>

				<?php wp_link_pages(array('before' => '<p><strong>Pages:</strong> ', 'after' => '</p>', 'next_or_number' => 'number')); ?>

			</div>

			<div class="postmetadata">
					<?php if( function_exists('the_tags') )
						the_tags(__('Tags: '), ', ', '<br />');
					?>

                    <div class="sharezone">

                    <a name="fb_share" type="icon_link" href="https://www.facebook.com/sharer.php">Teilen</a><script src="https://static.ak.fbcdn.net/connect.php/js/FB.Share" type="text/javascript"></script>

                     | 

                    <?php if(function_exists('wp_print')) { print_link(); } ?>

                    </div>

					<?php edit_post_link(__('Edit'), '', ''); ?>
			 </div>
		</div>

	<?php endwhile; ?>

		<div class="navigation">
			<?php previous_post_link('? %link ?') ?>
            <br />
			<?php next_post_link('? %link ?') ?>
		</div>

	<?php else: ?>

		<p>Sorry, no posts matched your criteria.</p>

<?php endif; ?>

	</div>

<?php get_sidebar(); ?>

<?php get_footer(); ?>

Do you find the bug?
Thanks & Best