Add page-link after post content. Before plugin

Since FB comment box is within content, to add page link in between actual content and fb comment box, you have to add filter to content that runs before fbcomment filter does. you can do that by using priority argument in add_filter function. You can set any number in priority that is lower to that set by fbcommentbox filter.

add_filter ( 'the_content', 'my_wp_link_pages', 98 );

function my_wp_link_pages($content){

$content.=wp_link_pages( array( 
    'before' => '<div class="page-link">'.__( 'Pages:', 'themejunkie' ),
    'after' => '</div>'
) );

  return $content;
}