title: Doctrine's Many-To-Many Self-Referencing and reciprocity
body: <p>By default, self-referencing <code>ManyToMany</code> relationships under Doctrine involve an owning side and an inverse side, as explained in the <a href="https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/association-mapping.html#many-to-many-self-referencing" rel="noreferrer">documentation</a>.</p>
  
  <p>Is there a way to implement a reciprocal association whithout difference between both sides?</p>
  
  <p>Following the example in the docs:</p>
  
  <pre><code>&lt;?php
  /** @Entity **/
  class User
  {
      // ...
  
      /**
       * @ManyToMany(targetEntity="User")
       **/
      private $friends;
  
      public function __construct() {
          $this-&gt;friends = new \Doctrine\Common\Collections\ArrayCollection();
      }
  
      // ...
  }
  </code></pre>
  
  <p>So, adding <code>entity1</code> to <code>entity2</code>s <code>friends</code>  implies that <code>entity2</code> will be in <code>entity1</code>s friends.</p>